Use it's (with the apostrophe) only when you mean "it is" or "it has." For example: It's time to go. (It is time to go.)It's been a long time. (It has been a long time.) Use its (without the...
Deride means to make fun of in a wicked way. It is similar to jeer in that it means to taunt. "Old hands at gaming will deride a new player with the cry of 'noob!'" It often is used, like I just did,...