Othello help me with homework: n his second soliloquy (2.1.308-334), Iago is “thinking out loud”

In his second soliloquy (2.1.308-334), Iago is “thinking out loud”– planning his course of action and giving reasons for it. What is he planning to do?  What reasons does he give?  We already know he is angry at not being made lieutenant, but what other reasons does he give now for getting back at Othello?