If you're from the UK, then follow the steps without using the proxy:
Copy & paste
Copy & Paste
Once the page loads you should see this:
To get the guitar you must the video below:
To get the t-shirt you must invite another player.
For that to happen, you must use a manual proxy:
Once you have chosen a proxy, you will need to copy and paste this link:
Than you should see this picture:
Scroll down and enter the contest by answering the question and you're done!