Arranging samples on a pad is a personal preference, whatever works for you is the right way.
Samples are available on disc (sample libraries) and you can find them online. You need just enough computer background to move a file onto an SD card, and that will get you through 90% of the process. No folders or directories, just put them straight onto the card.
But sometimes it helps to tweak a sample in a sound editing program, just to make sure it's 'tight'. That is, if there's any space (dead air) in front of the actual sound in the file, it won't trigger exactly when you hit. Obviously, with rhythmic hits, delays aren't good. So, you edit the file to remove that dead air, maybe tweak the EQ, raise the volume, or add an effect, and then it's ready to save to the card and load into the pad.
Remember, this unit takes only .wav files (16bit 44.1khz, 22,050, or 11,025) and plays mono samples, although you can pan them to make a stereo output for a kit, for example.
Once you get the hang of it, it's all very quick and easy.
Bermuda