Membergate is a standalone complete solution, so it is not possible to just apply MemberGate to your site. It has everything already built in. That includes membership management, shopping cart, affiliate program, content management, discussion forums and much more. It is usually pretty straightforward to simply copy and paste existing content from your site into the Membergate content management system.
If you have a very large site with many files in the database, it may be possible to import the data. You'll need to write support@Membergatesupport.com with specific information on the database. For example, how many records and what type of databases. They will have to see a small sample of some of the records to determine if there's going to be an issue importing them.
You can keep your current site live and work on Membergate in the background. We will give you the IP address of the new site and you will be able to access it from there. When the time comes to make your new site go live, we will instruct you on how to change your domain name server information so that is pointing to your new site. That way people do not have to see your new site under construction.