If the low beam cut off is flat then nothing to modify. If it has a 'kick-up' to the right then blank over (with black tape or similar) the wedge shape outline on the right hand side of the dipped beam lens cover, (vice versa if you have rhd halogens going to the continent from the the UK).
The chaps with projectors have it easy just turn the lever on the bulb holder to rotate the bulb.
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