I have thrown away the box with my serial number on it, and i don't know how to find that number. How do i find that number so i can activate the program.
If a re-install of a previously activated/registered installation then you can find your serial number as follows:
Using your favourite web browser, browse to the magix.com website
Click the My Account icon, top right of the home page
Login using your email address and password you registered the software with
Click My products this will take to your registered products download links and serial numbers.
If this is a first time installation, IIRC the serial number is on the disc sleeve rather than the box. If you have thrown this away then you will have to contact support at magix.com.