Use a wig cap, the kind used when cosplayers go to wear a wig, to keep your hair content, can buy in disguise stores or in internet.
If your headwrap no has velcro closure, put now around your neck.
Put lekku like a swimming cap.
Insert or remove stuffing to suit your head.
Here you can wear a tight bandana or use prosthesis glue according to your needs.
Prosthetic latex glue like Kryolan Mastix, Pros aide, etc. you can buy at costume/disguise shops or online.
I recommend Pros-aide, medic grade prosthetic glue. For me is the best. But others can work well for your skin.
Pros-aide works like contact adhesive: apply a little glue on the two elements to paste (lekku and skin), dry (have patience, I did not have and learned that it was best to wait), paste skin and lekku. Hold down for a few seconds.
To take them off to use adhesive remover/solvent, I think that alcohol or wipes cleansing also works, but better glue Remover.
Cut the excess of forehead if necessary.
Practice, experience is the best

Here a video that we recorded a few years ago, I hope can help it.

If has small head, make a fold in the nape and glue it with props-aide.

Now I know paste very well with props-aide, here can see a glue resistance test … I will do no more… after awhile trying to pull me the lekku myself without solvent, a pilot friend helps me… No cheating, he is really pulling!