This whole topic is explained in "Star Wars - Incredible Cross Sections" (which is an absolutely AMAZING book, btw). And stop ripping on the guy for asking a question.

TIE fighters set down into a docking bay and the pilots get out via ladder. The TIEs are then taken to maintenance (if they need it) and "docked" into these overhanging holders from the ceiling, ready for their next mission. Pilots get to them from catwalks along the ceilings before being launched. This means that most pilots will never be in the same TIE fighter more than once.

Edit: Here is the picture of the launching dock from the book (minus the descriptive text.) But you can see the catwalks and the two TIE fighters turning into the launching queue from the back of the line.