2000 Chevy Cavalier When do I have to change my trans fluid

Hi,

I just wondering, when do I have to change my trans fluid on my cavalier 2000 since I just bought it last month. It has 87,000 miles on it.

also how to check the trans fluid on my car whether it's still good or not? Since it doesn't have the stick like the stick for engine oil?
BTW, how often do I have to change my trans fluid?
is it base on miles? Or color from the trans fluid?

any suggestion?

Thanks for your answer.