Help!! How can I become a positive person!?

So im a very passive aggressive person but I dont want to be. I want to do a lot of fun things my age and I want to be happy but often I feel like things like my anxiety hold me back from being happy. I'm constantly irritated at my friends for no reason and their choices and instead of telling them they upset me I become passive aggressive because theyre not doing anything wrong so it's not like I can straight up tell them they're upsetting me I'm simply irritated because my anxiety causes me to be. This community is always incredibly helpful and supportive so I figured I would give it a go at my question. How can I become a more positive and happier person that's not so passive aggressive and irritated all the time ?