How can you tell which pokemon card comes from which pack?

I have gotten a tin of these pokemon packs a while ago for my friend. He eventually gave them to me and I only wish to sell them. But I would have to know what pack each pokemon card comes from. I know there are a lot of reprint of different pokemon cards and such, so how would I be able to tell which pokemon card came from which set? I am a noob at pokemon and never played the card game and never will thus my lack of knowledge.