I made an armour mod using 3ds max and í can't import it into the GECK, It messes up the model http://www.flickr.com/photos/50868892@N08/4979303680/ . So how do i do this properly? is there a tutorial anywhere?

you have to rig it.

Start by browsing the articles section at Fo3 Nexus, such as this one: http://www.fallout3nexus.com/articles/article.php?id=196

Notice he mentioned max not blender.

through google you will find max tutorials.