So you own a domain already which is the hardest part. Some websites like GoDaddy.com offer their own FTP (File Transfer Protocol) which is what you need to transfer your files to the server. There should be some sort of tutorial if you google based on who you purchased your domain from.
If the web host does not offer a free FTP there are free ones such as FileZilla (which I prefer). Once you download one of these you need to enter your exact web domain, username you used to create the website, and the password for it, then all you need to do is drag and drop your files.