Office Desk Plans

What's the name of the rail wheels and drawers and keep things that allow them to slide easily? and what type of inexpensive wood would be good for a high office?

You are looking for "drawer slides." They come in different thicknesses. If they are drawers that contain the files, make sure you buy some that are strong enough to classified files.
If you want something fast and cheap, you can buy a door and put on trestles or ready made file drawers.
If you want something to look good and last, I suggest maple plywood for flat surfaces and drawer fronts. It is a tight grain pattern and is easy to work. It has a contemporary look with a clear finish or spots of light. It may look traditional with a cherry stain or more.
Plywood is heavy and strong and will not need much reinforcement. If it is to be a desk on which you write or draw, to avoid cons plywood that has a strong grain pattern as red oak or ash. (In time, the soft tissues in the grain will at different rates as the most difficult fabrics and you get an uneven surface.) With all the plywood, you will need the wood edge to finish the raw edges. Meanwhile the office of style you want, it could be a simple flat edge, or if you want a traditional look, you can get with an ogee edge (S), detail.
If you draw your design in advance a few meters will be the big pieces for you a small fee. If you do cut yourself, be sure your blades are sharp, then you'll have less problems with the outbreak. If you do not have a design already in centers such as Lowe's or Home Depot do-it book-yourself designs, or you can visit the library or bookstore well.