You put a play list or several cards into the "Next" field at the top and set it going with the on/off. If random is ticked the cards play randomly, if not ticked the bottom card plays, then drops into history when done and the next card at bottom starts. Bit like an egg timer works I see it as. Repeat allows it to run over and over if ticked. There is no doubt a thread about but would have taken me longer to find it than type this I think. Someone will no doubt find it.
As for adding pictures you do not seem to have that option in this part of the forum. Normally next to the smiley face on its right is a small picture icon, but it's not there for me either. So not just you. Probably need to check the rules about pictures. Some threads don't allow nudity.
Lots of threads all over to help you get going, but for 3 days you have cetainly got the buying cards part sorted.