Philippe-
Welcome to the world of Hi-Lo. You will find a great deal of information on this topic from the people on this forum. To start, however, I would go to the search function and put in "roof repairs". You will find a number of posts and discussions and, if diligent, whole folders of photos detailing other's efforts in this endeavor. Reading those, first,may help you narrrow down your questions.
There have been others with holes in the aluminum roof- I have one (aluminum roof) and have not had the issue, yet, but it will, no doubt, emerge at some point. You will get advice from people to check for water damage and it is good advice. You may have to remove inside ceiling panels etc to get a good look.
Also- letting everyone know what year your camper is will be of some help. Good luck. You will find much advice here.
rick