Back in '99, when I went to WDW for the first time, I, too, was a bit nervous about figuring out the transportation system. Man, a lot of worry about absolutely nothing!! When you get to your resort bus stop, you will see that the buses all have the park name across the front and the side signs...so, you'll know which bus to hop on. When you are ready to return to your resort, just check out the board, outside the park gates, to see which number your resort is. You will see that the resort name is hanging down, below the bus stop number at each boarding area. Couldn't be easier.
Now, it does get tricky when you start going from resort to resort. You have to head to a park, usually, and then transfer to the resort bus of your choice.
If you tell us of any specific concerns, perhaps we can direct you or just calm your fears. The bus system is really quite good at WDW...even my dd had it figured out by the time she was 10.