10.1 doesn't exist anymore, you can download the software through your esri customer profile if memory serves, but you would be advised to contact tech support to see if you 10.1 license can be used with the current version.
Where did you obtain a 10.1 license? Is this from an educational institution?
That version is very out of date and my be available from an institution download instead... but it would be best to confirm if it is with an educational institution. It would be the rare case that they sent the students to wander aimlessly without specific instructions on where to get the software, how to download it and how to install it.
In any event ArcGIS for Desktop Student Trial would be the portal, but a 10.1 license isn't going to activate a newer version.