3d object

how to put a 3d model on a other object (and when that
object moves,then the 3d model haves to "follows it"
how to make something like that

That's what the Parent parameter is for.
Example

Body = LoadMesh("Body.b3d")
LeftArm = LoadMesh("LeftArm.b3d",Body)

Now whenever Body is moved, LeftArm will follow.
If the two entities are already loaded in, then use:

EntityParent LeftArm,Body

ok thanks

If you have a boned b3d mesh then you can;

Player = LoadAnimMesh("Player.b3d")  ;Load the player
Player_rightHand = FindChild(Player, "bone_rightHand")  ;Find the right hand bone

Sword = LoadMesh("Sword.b3d", Player_rightHand)  ;Load a sword model and attach it to the right hand bone.

attach things like this.

yes it works, thanks

How can you position the sword, and still following the right arm? it may happen that the sword may not be were you want.

Mesh commands modify the geometric data, use them.
Or just create the art correctly up front. It will be attached at the 0,0,0 point so make sure that the holding point of your item is there.