Once you have pasted your URL into the box, this is what you should see, obviously with your URL not mine;
You are almost done. When you hover your mouse over the white arrow in the solid blue box you will see the text 'apply' appear, click the arrow and now your button has been linked to your URL.
Save your post.
View your post and when you click on your button it will take you to your log in page. Now wasn't that easy? This call to action button (with the appropriate text) can be used to sell products from any of your affiliate sites like Amazon for instance.
Make sure you write an enticing post so clicking the CTA button is the logical conclusion.
If you liked this tutorial, you would be doing me a great favour by clicking the green like button and to add icing to the cake a little comment would be greatly appreciated just so that I know this has been of some use to you and that you might want to see another tutorial from me.
Thank you so much! Have fun with this and create brilliant CTA's for your site, they are magic!