The confusing GET,POST

the data communication method drives me crazy recently and there is little case online can fully matching the case i am facing so i need to think about it myself

as i am not familiar with the "get" "post" method in any language doesn't matter JS or Python or HTML

So I need to totally learn from the beginning 

And yesterday I found the "re_path" in Django and I hope I can combine this two together and get something 

Good Luck