Process is simple. A quick google will probably show you a video or diagram so you know exactly which screws to take out. then once the cover is off you might need to take 2-4 screws out, depending on how it is mounted and just put the new drive in the exact same way.
This page might also help
I assume it is not under warranty at 13 months? If it is, a call to them should get a new HDD sent out for free.