I would like to add a friend of mine to my friends list, i have showed him the website and he has created an account, I want to send him a friend request but cannot do so becuase it only works for if they are not on the website already, how can I get around this?

find out his account name & then add him through it.  HOW?  simple.  click at MY HOME.  Then there click at MY FRIENDS and finally there look at your left hand top & click at 'add friend'.  The rest is self-explanatory.