On the new computer reinstall from disc if you have them or download the programs again from the Magix website and install.
To download again go to magi.com, click My Account top right of the home page and login using the email address and password you registered the software with.
On the next page click My Product on the left side.
You will now be presented with your registered products, serial numbers and download links (if still supported)
If when you register / activate the software on your new computer, you have already used up the allowed number of activations a dialog box will appear telling you so. You will need to contact Sales at Magix to have the counter reset - give them the reason why you need a reset.
Once you have done this transfer the projects and resources from the old computer and uninstall the software.