Here is a link to the migration / upgrade resources: http://support.sas.com/software/updates/index.html
Please note you will require a complete new install based on a new planned deployment provided by SAS (you can't copy SAS between operating systems). You may also want to consider upgrading to the latest maintenance level at the same time - SAS 9.4M5.
If you do not have specialist SAS installation expertise in your organisation then I would strongly recommend getting help either from SAS or a third party to properly plan for and carry out your migration.
Testing all of your SAS applications, once migrated, to ensure they work correctly and give you the same results will be an essential requirement.