My b2evolution Version: Not Entered

This might sound very stupid question for you guys. I tried to search but the threads related to it are a bit confusing for me.

I have b2 evo with 3 blogs. The blogs itself are in a folder public_html/b2evo.
The files are blog1 blog2 etc.,
I tried changing the URL from back office to some thing like http://something.myurl.net
But it doesn't work that way. I tried making a subdomain from the cpanel and also tried redirecting it to the blog URL. I just dont want it to be /blog5 or w.e. I want it to be a subdomain with out the index.php?=blog5 or things like that.

Thank you .