Multi-domains, multi-sites, domain mapping question


I am getting overwhelmed. I installed too many plugins at once and took a few days off. Now I am not sure where to begin. Right now I want to test whether I can create new sites in my multi-site network. I tried to create one, but the site is not working, see

What needs to be working in order to create new sites in the network, as the superadmin? Where do I go to create the site? What do I need to test? I recently moved my hosting from Blue Host to Host Gator because blue host didn’t allow for wildcard subdomains. Perhaps I didn’t finish the change over completely?

I am pretty sure I installed muilt-domains, domain mapping and several other things and now I am confused about what does what.