Easy peasy! Just use the metro and make your way to "Santiago Bernabeu". If you allow yourself time, you can arrange a tour of the stadium, buy tickets for a game and visit the RM Store, which is in a little shopping mall at the northern end of the stadium. If you only have a pocketbook or downtown map of Madrid then you wont see it as its someway out of the centre. If you fancy looking around Atletico's stadium-and all grounds look better in red and white-go to metro stop "Piramides"