This assumes you have the Subversion client installed.
1. Create a folder where you want to check out the files
2. open a command shell and cd into the folder
3. enter the command svn checkout https://forgesvn1.novell.com/svn/mojoportal/trunk
If you have Subversion installed the files should start coming down.
You can also browse the mojoPortal source code using the link from here:
http://developer.novell.com/wiki/index.php/Mojoportal_Subversion