Use the BBC code for posting the pic, not the URL link.
There are no manuals typically for any camper. There almost never is a diagram except a drawing in a glossy pamphlet showing the layout.
The only thing "truck camper" about your truck camper is that it does not have wheels, but gets chained down to the bed. Everything else is camper, so a better place to learn is in the general camper section.
Sounds like maybe this is a pop-up??? If so, then there are thing to learn there, but surely your seller told you how it goes up and down. There should be basic instructions for that part of camper. But you said"hard side" so maybe not.
All the appliances and windows and doors are camper parts, not unique to a truck camper. Just read about campers and you will learn.
If you are asking to be told everything you need to know about owning a camper, then just delete this whole thread and refer to hundreds of other threads that will contain the answer since it will take hundreds of post to give you that answer. If you have specific questions about general camper things, then post in the general camper section and get a bigger group of people to discuss with.
The unique thing about truck campers is they are chained down to the truck, otherwise it is just a camper, campers have many things in common with other camper, regardless of the brand or year made. a $2,000,000 motorhome might have the exact same water heater that your $800 TC has for example.