@ GLaDOS
The best thing to do is load upload your project and then someone can have a look at it. It's easier to fix a problem if there's something for people to play with.
As for actually making your game, i think the essence of your problem is this:
Quote: "i have no idea what to do.all i really want is just a enemy that shoots me,a health bar and a gun with ammo"
Someone could just tell you how to do this but I'm kind of guessing that you want to learn to make bigger and better games. So this is my view and my advice, take it or not as you see fit.
The way I see it, there are two things going on here.
The first is what I would call the concept design stage. What you have so far is a vision for what you want the game to be. I think it's actually quite a good vision, brief and too the point. However, what you need to do is put some details in so you need to write down the details of what you want. For such a simple idea you don't need to spend too long doing this and will probably be no more than a page long.
This is the sort of thing I would probaby write:
1) Standard WASD and mouse FPS controls (you've already done this).
2) Player sliding collision against walls.
3) No jumping or crouching
4) There will be a cross hair in the centre of the screen.
5) Player only has a single weapon and there's no close combat.
6) Player uses left mouse button to shoot. Player's weapon is single shot so they must release the left mouse button and press again to fire another shot.
7) Enemies are static and always point at the player.
8) If the enemy has a clear line of sight they will immediately shoot at the player.
9) The enemy will fire a single shot, then there will be a delay of half second between shots.
10) There will be random element to simiulate the npc's shooting ability (to give the possibility that they might miss the player).
11) Bullets will not be visible and all hits will be decided by simple ray casting
12) There will a visual indicator to show that they npc is shooting (muzzle flash or whatever).
13) and so on (there is a whole bunch of other stuff you need to consider like how much damage does single shot do, when happens to the npc when they die etc)
This is just an example to show you the sorts of things you need to consider but what I've done is try to make it as simple as possible and it can always be expanded upon. However, I think it's important to write down things that you don't want as well as the things you do want, as this immediately clarifies any ambiguities.
The next stage:
This is the problem solving stage. By this I mean you look at each point in the list above (or you're equivalent of it) and work out how you're going to code each bit and how it's all going to work together. This is going to depend on how good you are at problem solving and turning ideas into code.
So, lets look at point number 5. What needs to happen in order to score a hit on an enemy is:
5.1) The cross hair needs to be on the enemy
5.2) The player presses the left mouse button.
So, how do you determine if the cross hair is on the enemy? There are a couple of ways but I would recommend using sparks collision dll and doing a ray cast. A ray cast requires a start and end point. So the start point can be the camera position (which you know). The end point is some distance away directly in front of the player. The actual distance will depend on the size of your map but should be at least the range of the camera (which by default is 3000 units away. Now the trick is, when exactly is the end point of this ray cast? This kind of question is the fine detail of game creation. There are many different ways of doing this and we still haven't gotten onto actually using the ray cast, we're just trying to define its end point. This is why I kept the game play as simple as possible because you're going have to go through this for everything in the game (to a greater or lesser extent depending on what you already know how to do).
I generally describe problem solving as a combination of knowledge, creative thinking and experimentation, wrapped up in methodical thinking. The knowledge part is about learning things, looking at example and demos (everything you want to do is somewhere on the forums). Creative thinking is a little more difficult to understand, I don't think many people get it. In this context it's not about art or graphics it's about thinking about things in a different way, making connection between what seems like disparate bits of knowledge and coming up with ideas. A good way of cultivating a creative mind is to come up with as many different ways of doing the same things. So for instance, how many ways can you think of to get a cube to move in on a circular path? I can think of at least three. Experimentation is another easy one to do. This is all about writing short and simple code to try out ideas. So if you've never done ray casting before, I would suggest just writing a simple bit of code using primitives and just explore how it all works. It's also easier to get help with small bits of code you can put in code box. The methodical thinking is absolutely crucial and is all about defining the problem and then planning out the solution. It helps to highlight areas where you lack knowledge and exactly what it is you need to do. The more you problem solve the easier it becomes but it really does take practice.
My intention is not to scare you off, what you want to do is fairly easy and you're bound to find examples on the forums. But even if you find something you still need to understand it enough to bring into your code. And if you want to expand your game, you're going to very quickly stumble into some potentially complicated problems. My advice is to keep everything simple and then build up.
Anyway, I hope this makes sense and is in some way helpful.