Your - possessive – Belonging to the person the speaker is addressing.
You’re – a contraction of “you” and “are”
USED IN SENTENCES
Correct: You’re about to run off the road, watch where you're going.
Incorrect: Your on the right path, keep it up.
Correct: Your cell phone just fell out of your pocket.
Incorrect: Thank you for letting me use you're cell phone.
The easiest way for me to remember this is simply slowing down and asking, would I say you are here if not saying you're. If it sounds wrong, and you're meaning to talk about something belonging to somebody, you'll know right away which version of your or you're to use.