Wiring a toggle switch for headlights is pretty simple actually. All you need is a wire from the positive battery terminal to the switch, then a wire from the switch to the headlights. You'll want to disconnect the stock harness wires that deliver power to the lights, but leave the ground wires if you can. If not you'll need extra wires that run from where the ground wires were, to somewhere on the frame of the tractor (remove paint from that spot to ensure proper ground).
That should be all you need unless it's some sort of fancy high/low beam setup, in that case you'll need someone else to explain it because I don't have a clue about that
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'70 107 with k301 engine swap
'71 106 with 38" deck
'70 147
R with factory replacement k321, 42" deck
'61 Original with 38" timed deck
'63 70 "pinkie"
1863 with 54" deck
'46 Farmall H, '50 Farmall Cub
105 x2 (parts)