I know this is an old thread but I wanted to post incase anyone is like me and really struggling to get a payment option on their website. To add Lawpay I clicked on "edit header" then changed the text on the "contact" button to say "make a payment". I then put the hyperlink given by Lawpay on the line beneath where I typed "make a payment". It worked and I only had to spend two days figuring it out ;)