This is not a DIY beginners project because the exterior cladding is not meant to have additional siding screwed into it.
What are you trying to achieve? Fix air leaks? Fix water leaks? Provide more insulation?
It depends what kind of siding you'd like to add. Here's some info. https://mobilehomeliving.org/mobile-home-siding-options/ You can also paint the siding or only replace damaged areas if you are trying to cosmetically update!
"Mobile home siding installation is a bit more complicated than your average home repair, especially if you select one of the more laborious siding styles, like stone or wood. But with the right tools and some patience, it is possible to install or repair siding yourself."
Have you thought about a vinyl wrap? Popular with car owners, now used to refresh the doors and sides of kitchen units, I've even seen it done in a bathroom to cover a multitude of sins in a rental home (where the choice is limited to the owner redecorating or not bothering).
OK, so it'll cost, but nowhere near as much as replacing all the siding.