Well first you need to register your Skrill account via the banner above, after that you'll need to login and the page will look like the example below.
After you've logged into your Skrill account you see a page that looks like my back office example below
And as you see I've put an arrow to the place where you find your ID number what you need to fill in the box on the page with all the promo tools... There's only two way's to go to the promotion page and that's by clicking on the link Skrill Affiliates here and on the bottom of the Skrill home page you'll see the same link
The Skrill Affiliates link is on their home page's footer as you see pointed out below
Next if you scroll down until you see How To Promote Skrill
It will look like you see below, I've pointed out with a blue arrow where you need to fill in your ID number and then you can click on the subjects below that to unfold and see your promo images and if you click on the image link to see the code you're gonna see that folding out below the images.
Now copy the code and paste that in a new text-widget on your wordpress website where you want to have it showing up
There's also a Skrill VIP level which you can get via the banner below