Is cryptocurrency legal in your country this time? If not, you can use the global exchange.
But, I wonder that you only want to know about trading Bitcoin to Skrill?
I am trying to search what Skrill and I found about this one:
https://www.skrill.com/en/So, you can do it by following the steps that are given in the following lists:
Tutorial on YouTube
https://youtu.be/vx94ha-HE_QAnd also there are some tips about it:
https://www.skrill.com/en/skrill-news/cryptocurrency/forex-traders-buy-crypto/Actually, you can also use Paxful. But ensure that it is also available.