there, their, they're, theirs, there's

There or there, means in that place; yonder--
Put my soda over there.
Don't leave that there.
There or there may also describe a state or condition--
There are no more sodas.
There is out house.

There's or there's is a contraction ( short, informal form ) of  "there is"--
There's no more soda.
There's the place I was talking about.

Their or their ( rhymes with there ) means belonging to them --
Where are their sodas?
Here are their sodas.

Theirs or theirs refer to the things belonging to them--
Don't touch those sodas. Those sodas are theirs.
Are these theirs or ours?

They're or they're ( rhymes with there ) is a contraction (short, informal form) for "they are"--
They're going out for a soda.
They're going home now.

Now that you know that, you can say--
"They're going there for their sodas." 
 "There's soda in the fridge that's theirs."