to assign a weapon to a weapon bank, go to the ship inventory screen and move the mouse cursor over the weapon you wish to assign (on the ship hard points) and press 1-2-3-or 4 and the weapon under the cursor will be assigned the new bank number.
Note you can have several weapons assigned to the same bank, I like to assign my left weapon to 1 and the right to 4 and the light forward weapons to 2 and the front heavy weapons to 3.
I hope this helps. (and I'm sure tis info is better described in the docs/readme file.
Cheers!
