What should I do first?

One of the first things you should do when we set up your account is be sure that your email is set in cPanel. There is a link near the top of the page that says

Just click the word 'here' and be sure that the address is correct. This allows any space or service relating issues to be communicated to you.

Also, remember to backup your site on a regular basis, most users take a backup once a month, more often if you update your site frequently. Also take mysql database backups if you use CMS, forums, shopping carts or similar scripts.