I take it you have taped all the lense of the OEM headlight? FFS don't let any resin touch the lenses as it will attack it. Use a couple of layers of masking tape if you have to. Cover everywhere you don't want resin.
Next get yourself a couple of throw away coffee cups (cardboard and clean) mix only half of your resin at a ratio of about 2% with MEKP hardener. 100ml resin:half teaspoon hardener(catalyst), mix well with lolly stick (or old screw driver

).
Hopefully you have precut your glass to shape required.
Now brush resin on tape and lay glass on resin, always work the resin úp'through the glass, don't try to push it down. Work with a brush and you will see the emulsion binder start to breakdown in the glass (the fibres start to move independantly).
Lay another layer on and damp down with resin until saturated.
Work with brush, now you can consolidate with a brush well enough on a job like this with a brush.
The glass they normally give with kits is 450g so 3 layers will be adequate, a couple of mm.
Leave it to dry, preferably give it a bit of sunlight.
The next day strip it, then surface sand it with something like 80g, skim a bit of nikky in if wanted, sand again.
Finally if you want to mix a small amunt of resin and liberally apply to flow the surface smooth, allow to dry well and sand back with something slightly smoother, to give a prior primer finish.
Good luck and don't breath too many fumes, I makes you go all weird like Hoffy