Make sure you write you activation key down. You will need it to complete the installation
Click on “Get Downloads”
Click “Get Downloads” to go to the download section.
Select the appropriate download for your operating system. The direct download is always faster but cannot be continued if your internet connection fails. If you have an intermitant connection, choose the “Download Manager” version.
Start your download
The installation file will download. When finished click on “Launch” This will run the application setup
Enter the activation key from earlier in the installation
Accept the terms of agreement
The Mathematica application is now installed on your system.