How do I send US qualifications to the London School of Economics?

I am not sure how to provide proof of my qualifications in a way that the LSE will deem appropriate. They ask for signatures from test officials etc., I'm not sure how to get these from the college board. Is it enough simply to use the college board's test sending service? They have LSE listed as a school hey can send scores to but I'm not sure if this is adequate by itself. If there's anyone that can help me out that went through the process of sending AP scores to LSE any help would be much appreciated.

Its all on the website.

http://www.lse.ac.uk/Study-at-LSE/Undergraduate/Offer-Holder/Information-for-Offer-Holders/Submitting-certified-copies-of-qualifications

https://lfylive.lse.ac.uk/lfy/tc/enquiries/enquiry.html?a=4&q=502&searchString=

Thanks for the reply, however, even after reading the info in the links you provided I'm not sure whether or not AP tests sent directly from the college board will be considered certified. It says "if I wish" I may also return the proof of qualification form that I was sent in the mail that would effectively need my principals signature and a stamp from the school? What's the deal with that?

I am not sure how to provide proof of my qualifications in a way that the LSE will deem appropriate. They ask for signatures from test officials etc., I'm not sure how to get these from the college board. Is it enough simply to use the college board's test sending service? They have LSE listed as a school hey can send scores to but I'm not sure if this is adequate by itself. If there's anyone that can help me out that went through the process of sending AP scores to LSE any help would be much appreciated.