When to use, "Their," "There," and, "They're."
Their, There, They're
Their-Is a possessive adjective/adverb. It is used to designate ownership of an object or an action. For Example;
The teams cohesion was impressive, their unity was amazing to witness. Or,
They stood up after their long tirade, their irritation all but palpable. Or,
Their time together had come to an end; there was no place to go but home.
In the first sentence, "their," qualifies and designates unity as belonging to the team. In the second sentence, "their," ties irritation to whoever they are. And in the last sentence time is tied as a direct possession of, "their."
As you can see your use of the word, "their," should refer directly to an object, either a noun or a verb and should help to qualify and designate that noun/verb as belonging to something or someone else.
There-Designates a specific place in space or time. It describes through direct indication a temporal or proximal vicinity. For example;
Put the cargo over there, in the corner of the room. Or,
I remember us five years ago in that house, we were so much happier there. Or,
I've been running here an there looking for you.
And so the word there is a direct object, identifiable and describable. and is tied to a verb such as, "Put, " "remember," and running," respectively.
They're-Is merely a contraction of the term, "they are," So it is simply the conjunction of a pronoun subject with a verb. Just as, "It is," "We would,", or, "she had," contract a pronoun subject with a verb to form, "It's," "We'd," or She'd." For example;
They're destined for big things is they keep their dreams alive. Or,
Whether they're guilty or not is a question for the courts. Or,
When this is over, they're not going to be pleased.
Note here that as a the verb half of the contraction, "They're," the verb "are" is not always the active verb but sometimes acts only as an tense indicator for the active verb.
Please post any questions and happy writing!