The two most played continuations are Ba4 and BxN.
They're very different, so I'd suggest you try one of the two for some time and look at theory after the games, in order to see if/where you went wrong and why, and then try the other one in the same way. So that you can see with experience which kind of game you're more comfortable with: the maneuvering one, when all pieces stay on the board and both players try to organize an attack without dissolving the tension in the centre which follows Ba4, or the exchange-pieces oriented BxN, when the centre is opened and play tends to evolve toward the endgame at a faster pace.
I'm a beginner......and i've been losing quite alot of games.... So... every now and then I come across the Ruy Lopez opening (as white). So what would be the best follow up when black threatens the bishop (a6)? I think it's called the Morphy's defence or something...
Thanks.