Your: You use it when you're talking about someone's possession 
Ex: Is that your lamp?    
You're: short for "you are" 
Ex: You're crazy 
There: when you're talking about a location 
Ex: "Have you seen my belt" "Yes, it's over there" 
Their: when you're talking about a group of people's possession 
Ex: why did you take their money? 
They're: short for "they are" 
Ex: They're at the movies right now 
Its: a possession of somebody or something 
Ex: Its tail is very long 
It's: short for "it is" 
Ex: it's necessary for you to use these concepts