I heed a lil help please

[raider51]

Im rookie also with this modelling thing but im trying to tell it point for point:
First, as Turkish said make sure your coordinate system stand at 0,0,0.
If you hasnt done so far, then now right click the model and click "convert to editable poly".
After assign the entirely model and in the upper menu-row click "mirror".
In the mirror menu click "instance" and click also in that coordinate window (x,y,z) you want to mirror at.
Now you have a mirrored body, all you have to do to move it into right place and thats the reason you have to set the coordinates at 0,0,0, because its pretty easy to click on the "move" icon in the upper menu-row and type 0,0,0 in the windows of x,y,z.
After you placed it you'd have two bodies.
Now assign the mirrored body and right click, select attach list and add the original body to the list, with materials and all.
If everything is fine you have one body but with a "cut" on the middle. You can check it easily, select the vertex in the modification window (the first one looks like a point) and move a point at the middle... because there are two points covering each other the second one is still stands.
To weld them, you have to roll the modification menu/vertex and you have to find the weld command:
Select upper or front view first, then switch off the "ignore backfacing" in the top of the modification menu, and with press the left mouse button assign the vertex points in the middle. If you done well, all of middle vertex points appear in red color.
Now all you have to do to weld it, click on the "weld" in the vertex menu and set threshold between [1-10].

I hope it helps, ive done it from memory if something wrong then post that.