1. Go to your Profile
2. Click Change Cover
3. Choose image from your existing album or upload from computer.
Tip: before uploading an image you can crop your picture to fit perfectly. The best size for the cover picture is 1140 px width by 428 px height. If you don't have a program to crop your images no problem. Go here: www.fotor.com/features/crop.html
Upload from your machine, crop (1140 x 428) and save. It's that simple.
If you have any problems, send me your resolution picture and I'll do it for you.