It's certainly possible to teach yourself board design; I did that myself, and have since done many boards from small adapters to 8-layer boards and BGAs...
There are a few steps:
- Choose the software package. Some (like ExpressPCB) are tied to a specific board house. Others (like the free Eagle) have limitations on size or selling boards. I started out with ExpressPCB and moved to KiCAD for personal projects. I have also used Allegro (but that's out of any normal person's budget...).
- Draw the schematic. While you may be able to skip this step for simple boards, I don't recommend that. It's easier to design and debug when you have a real schematic. You will have to create schematic symbols for components that aren't in the tool's library, so figure out that part too.
- Do the layout. If you have a tool that displays ratsnest (also called airwires - lines that show which pins need to be connected), that will help figure out placement. Start by drawing the board outline, and placing stuff that must go in a fixed location (connectors, switches, displays, triacs lined up for heatsinks). Then place the larger or many-legged parts to minimize airwires crossing each other. When laying out the board, think about other part orientations. Often I will rotate a part to simplify the routing. I will also reassign pins to I/O ports on processors (if possible) to help here.
- Post the layout and let others comment on it. Often, you are so involved with your own designs that you miss out on some things that will make the design better or simpler.
- Have the board fabricated. If you have a single sided layout (or even a simple 2-sided one where you can solder z-wires to take the place of plated-through holes) you can etch the board yourself at home. Otherwise, send it out for fab at a board house. If you look at some posts here or at DIYC, you will find some lists of good fabs. I have used PCBGeek, PCBCart, and Gold Phoenix in the past. BatchPCB, Seeedstudio, and DorkbotPDX have some interesting proto options, but it's often not that much more to get a whole panel done in China. Just be prepared to wait about 3 weeks. If you want it faster, ExpressPCB, Advanced Circuits, or one of the US houses can get it to you as fast as next day, but it's going to cost more.
/mike