Changing the url of my blog

I know there’s loads of people explaining this but I just can’t do it. I really don’t understand the codes.
So i have a blog effimai.com and I want to change it to fisfor.com so i don’t have my name in the url. I will first I think to have to change it to fisfor.wordpress.com and then buy the domain.
I can’t seem to do this. I have tried so many times. If someone could be amazing and give me simple instructions for a very simple mind I would be so utterly grateful. Or if someone can do it easily can they do it for me? I will promote you, your blog, anything you need at work, on twitter and on my own blog if you help me!
Thank you to whoever helps 🙂