If your resentments control you then you cannot let God guide you. The 4th step is all about people / places / institutions / principles that we have a resentment with. The things that we get angry and upset with. But, why are we angry? what is the cause? what was result?
There are form online to assist with the list and causes for working a 4th step. Or, you can just use page 65 in the Big Book. But at a base level
I had to look at 3 things; a) who am I resentful of b) what am I resentful of c) what was threatened
Start seeing that who what where and why did this happen to us. Now we can start seeing patterns in our resentments. And that will give us insight on where our triggers are. Once we realize this then we can choose how to react to these situations in the future and maybe we can make different choices in the future.