In that case, "it's" is a contraction equivalent to "it is". For a possessive, use "its".

Examples:

Practical advice from its members.

and

It's inspired by the stupid questions.

(What's the point of paying attention to this stuff if you're communicating clearly? Briefly, signalling. If I notice you've made a grammatical error, on average, I estimate you're less well educated or not invested in making the writing worth my while than in the opposite case, and am less likely to finish reading if I get bored or have to expend mental effort to understand what you're saying or something. Also, there's an aesthetic element: error-free writing is, ceter paribus, more pleasing to read.)

(Also, wondering if this was downvoted because someone thinks I'm incorrect, because they think I'm being an ass, or for some other reason.)