Brought a domain but now stuck, help?

So I am very new to this and I have just brought a domain but now I am stuck. My question is how can I transfer or move all the things I have done using the free WordPress website “so far” to the domain I have brought. Because before I didn’t have a domain and now that I do I want to transfer my free site to that. Is there anyway you can do this as I really don’t want to have to re-do everything. The web hosting company I brought my domain from already comes with pre-installed WordPress. Any help would be welcome thanks in advance.