The Zork tutorial is a very good read and should set you on the right path for making a text adventure.
But you should write up some design documents for yourself, before you even start coding. Discuss the plot (synopsis), how big you think you want to make the game (how many hours of playtime, and how many rooms in the game) and what kind of things you want to be able to do in the game with your character(s).
Planning out stuff like object interactions, potential party-based combat, or solo combat; how you want that combat to work, etc. What kind of inventory system you want, and what kind of puzzles you might think of adding to the game (find the key? find the hidden path? Defeat a certain enemy to unlock something? whatever you can think of, really).
After that's all said and done, you want to consult as much example code as you can find. Also you want to read through your DBpro help files to learn about the various features the language supports for graphics, text, data storage in memory and on disk, etc. User input will be important as well. You should decide whether you want your game to run in "real time" or not, before you do anything. If you want real-time changing world around the player even if they sit idle, then you will need to use an appropriate player input routine, because the standard DBPro input routine will not work for this - it will pause execution of your program until your player enters something and hits return, and it will do this each time the player is prompted for input.
I use an input routine I got from the codebase that takes input from the Windows Keyboard Entry Buffer. This allows it to check the buffer as someone types and simply move the buffer data into a variable that you then print out on the screen, where you want to show your player what they are typing. There are no pauses waiting for an entire input -> enter pressed scenario.
You are doing to have to design a lexer/parser system to interpret commands given by the player as well. This can be as disgustingly simple or complex as you like.. I haven't even begun work on that part of my game yet, but right now I am just going to go with a simple solution that tokenizes an input string and checks it from left to right for "key words" that are searched for either with an IF/THEN loop, or a CASE SELECT loop.
The tree itself can become complex once you start stacking up possible keyword combinations to make various commands, but if you have a minimal set of commands I believe it is a realistic solution at least for a beta phase of production.
A text adventure is a big undertaking. I started mine several months ago (granted I don't have a lot of free time to work on it) and design documents and having a clear vision of what you want to do, as well as how to tackle those problems in code, will be a big help to you.
Text adventures are/can be some of the most complex and difficult systems to develop for any programmer. They usually aren't recommended to new folks, even though that may seem strange. Due to the sheer level of mechanics going on with most games, it does become overwhelming to a lot of people.
So don't give up too easily if you have your heart set on it! I've gotten lots of help on the forums here when I was stuck or wanted opinions on doing something a certain way. People here are very helpful and very friendly to new coders.
