You need to partition it and format it for it to be shown in My Computer. If Windows 7 go to Computer Right Click then click on Manage Click 'Disk Management' You should see your drive. It will probably say unallocated . Right click on the unallocated drive, and choose 'New Simple Volume' Choose what format you want it and let it format.
Sony Xperia Z5 review: Hands-on with the phone which the Z3+ should have been