If you have more than one domain in your package and have not made any changes to the domains' destination folder, each domain will point to the root folder of your webspace. The "root of your webspace" is the main folder where you can store your website files and create subdirectories (subfolders).
After your web hosting package has been set up, a few files and subfolders may already be present in your webspace such as the logs folder which holds the logs of who accesses your websites, an initial start page named index.html or default.htm that says "This domain has just been registered" and some other miscellaneous files and/or subfolders.
If you have 6 domains all in the same package and have made no changes to the files, each of the domains are set to point to the root of the webspace where the initial start page is located and all domains would show this same initial start page when viewing the site in Internet Explorer, Mozilla Firefox, etc.
This Web space (/.) signifies that the domain points to your package's webspace (as opposed to a domain that is forwarded elsewhere) and the Webspace folder that the domain points to is listed in parenthesis. The slashdot (/.) signifies that the domain points to the root of the webspace as there is no subfolder name after the slash. If the domain were to point to a subfolder named website1, the destination would then be listed as Web space (/website1) signifying that when someone views this domain, the site files that should be used are in the website1 folder.
To separate your domains so that each domain shows a different website, you will have to change the destination of each domain to a subfolder that you create. Using the image above, it would be advisable to create one subfolder named 1and1help and use this as the destination folder for 1and1help.com so that way all website files for 1and1help.com can be stored in the 1and1help folder, separate from the other domain.
The same can be done for somedomain.com. You can simply create a subfolder named somedomain and use this as the destination folder for somedomain.com so that the site files are stored in this subdirectory and are not combined with the other domain's files.
You will have to Set Up or Change the Destination of Your Domain, making sure each domain points to a separate subfolder of your choice. Then you simply have to make sure that when uploading your files, you upload them to the correct subfolder used for that domain.