Help create a new hero (Heroes of Might and Magic 3: The Restoration of Erathia)

Help create a new hero! It is new, which is not yet in the game. I want to give the fanarms a +2 bonus to speed, and, accordingly, attacks and defenses are actually like others. Just like valeska gives to archers, only fan-arms. I watched a bunch of videos and climbed hundreds of sites but could not find how to create my own and with new unique stats. If anyone understands, please do not stand aside and write how this can be done. Huge thanks to those who responded!