You probably want to be using one of the popular libraries to do that.

AWS documentation isn't consistently good, and there are lots of decoys. So, if you wound up in some local minima that made it look like you had to implement the signing and such yourself, try a Web search that includes the name of your chosen programming language.

(A long time ago, I had to implement the AWS client API from scratch, but that's because I was using a fringe language that didn't have such libraries.)