It's so easy you'll be wishing that fuses would blow just so you can show off your mad fuse-replacing skills.
All you need is a replacement fuse of the same amp rating, and a little plastic fuse-pulling tool. You'll find both of these things in Airstream Life's Maintenance Essentials Kit.
The process is shown in the 1-minute video below:
If a fuse blows shortly after replacing it, you've probably got a short circuit somewhere. Stop and check with an RV technician. Don't replace the fuse with a differently-rated one!