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You mean you have domain name registered by someone else and you hosting with a different host if so all you need to do is change name servers at registrar to point to your host account.
Your host should have provided you with DNS settings.

What is the domain name in your Settings>>>>General as that is domain name that is used.
In permalinks you do not use domain name you suppose to use /%postname%/ so that permalinks use your title of page or post in urls.

This domain name markmcnee.com is it pointing your host account if so you will need ask your host to change DNS.
Some how markmcnee.com is redirected to http://www.markmcnee.site90.net
markmcnee is subdomain name of site90.net

then you will able to change domain names in Settings>>>General to your domain name.