I own a domain for a website, how do i use it?

In a nutshell, take time out to learn about html (hypertext markup language), the core scripting language for websites. Then learn about css (cascading style sheets).
That done you should be in a position to design your own website, which you can then upload to your domain using an FTP (File Terminal Process) uploader like Filezilla.

So after you have learned html, css and created your own web pages. Then you would need a host provider ( if you haven't purchased hosting space yet ) You would then attach the domain name to the hosting provider's DNS servers. Maybe they can do that for you. Then you upload your html and css and pictures files to their hosting server. You can do that using FTP programs or maybe your hosting provider has a web based tool to do that.