Disk Space

This indicates the amount of disk space that will be available to you on the server to hold your web site files.

Normally because HTML files are small, a web site (unless it has extensive graphics or database functionality) will be small, as low as 1 or 2 MB in most cases.

Use windows explorer to check the total MB of your site while it is still on your development machine. Then perhaps double your sites current size so that you have room to grow. When you check the total MB of your site don't forget to include the total MB of your graphics files.

A good rule of thumb is to assume approx. 50 KB per page (1 MB = 1000 KB, 1 GB = 1000 MB).
Domain Parking

This is the option to 'park' your domain name without actually having your web site up and running. This is a nice option if you want to acquire a domain name for your web site well ahead of having the web site itself designed and constructed.