Bonjour, Sylannh! Et bienvenue!
Exactly for your needs we have
the manual from zahar0z how to import models to HoMMV. Although question of how to export models from other games before it is an another topic...
Another problem -- zahar0z manuals are in russian. But I hope they still will be useful for you.
I must also warn you that this forum section is for finished mods only. So I will move your topic to
this section instead after you read the answer.
Wish you success in your endeavors.