Blood Frontier's avatar system is completely different to the way Sauerbraten does hudguns (Blood Frontier places the actual model in a set of replicated hands designed for first person viewing, this is to reduce content duplication). As such, there is no easy way to mix between the two, and if you are "new and don't know what to do" then I suggest you simply don't; Blood Frontier's content was created for Blood Frontier, using it in Sauerbraten is beyond the scope of support we can provide you with as an independent project.