Setting up MultiSites

I'm at a loss. I'm trying to setup multisite on the above. I just don't know what I am doing. Do you guys have anyone we can pay to set up the sites and show me how to use it. We have it somewhat set up, but it isn't working right with client logins and other stuff. I think we need the original structure of the main site and subsites to be set up so they function properly. I tried going through your setup but it errors out with a #500 error code. I'm just at a loss.