Welcome to x10hosting.
Download
DotNetNuke and before extracting it upload it into cPanel. I'm assuming you've worked out how to do this? yourdomain.x10hosting.com:2082 then File Manager.
Extract it (extract button top right).
Go to yourdomain.x10hosting.com/ and then where you extracted DNN.
I've never installed DotNetNuke before, so I can't help much now. I'm assuming it will be easy to install.
Hope that helped,
~Callum