some large high res. textures ( space stars, asteroid fields, black holes etc), you can basically make a large image, use dark basic to make the sphere (a very large one), texture the sphere with the space image.
As for your ships and space stations etc you'll need a 3d modelling program like anim8or
or somthing more sufisticated which will offcource need some ching ching.
but anim8or should be cool for beginners. Since i't a basic space game, you'll basicly need lots of spheres for plantes and the odd plane for say rings round saturn. still stuck then shout out again, i'll be glad to help