Find an easy song. "Yellow" by Coldplay is a good, slow song to use as a starting point, but many other popular rock and pop songs follow the same basic pattern. Listen for the beat and count it in fours: 1, 2, 3, 4; 1, 2, 3, 4.
Grip your sticks between your thumb and forefinger, using your other fingers as support. Use your left stick to play the snare drum. Cross your right arm over the top to access the hi-hat cymbal. Put your right foot on the bass-drum pedal and, for this song, keep your left foot off the hi-hat pedal.
Put your headphones on and press play on your CD or MP3 player. Wait until the vocal has started, and then start playing the bass drum. Play on the words "Look," "Stars," "Look," "Shine" and "You" in the first line. You are now playing on beats one and three of the four-beat cycle. Keep this rhythm going.
Clap along normally to the rhythm while keeping your bass-drum rhythm going. You should be clapping on beats two and four of the cycle. Then instead of clapping, play the snare drum with your left stick on beats two and four. Play on the words "At," "(no lyric)," "How" and "For."
Add the hi-hat by playing every time the guitar is strummed. Instead of playing on 1, 2, 3, 4, you play the hi-hat twice as often. So the hi-hat beat will be 1, 2, 3, 4, 5, 6, 7, 8. Leave your foot off the hi-hat pedal.
Play with all four limbs together through the entire song. The beat changes somewhat throughout the song so after some practice, you'll be able to improvise and deviate from the set pattern above to copy exactly what the drummer does.
Practice the rhythm as many times as you can, and always be aware of the four-beat cycle common to many pop and rock songs. Find another song you like with the same rhythm and apply what you've learned. Concentrate on the basic beat. Once you've mastered that, you'll be able to elaborate.