Ok, so you've found your library outside logic so you know it's all there which is good.
To call up EXS24 within logic, you must click onan instrument track (i.e. a blue one, and not a yellow audio one). Then go to the channel strip and hold click on I/O. Follow the menus Multi Channel/Logic/EXS24.
The plugin window then comes up in logic. Go to the black bar which is above the nob that says cut off and click once. Then a large scroll menu of instruments should come up, and just select the sound you want.
Once you have selected it, nothing will actually sound unless you apply it to something that you have programmed in. The sampler will work either on apple loops or on notes you have programmed in yourself, but nothing will sound until you actually have some notes in the track!
If that doesn't work, are you sure you have a full copy of the programme?