This free guitar lesson by Peter Vogl will teach you how to play hammer ons and pull offs. These are two of the fundamental techniques used to play guitar and are featured in almost every guitar solo you will hear.
Watch the lesson: Quicktime
Hammer ons are when we pick one note and hammer on to another using a finger on our left hand. Pick the open 5th string and then hammer on to the 2nd fret 5th string.

Your finger needs to have some velocity coming into the neck. It also needs to hit on the tip of the finger. Try this on all the strings.

Pull offs are when we pick a note that we have a finger on and then pull off with the finger on the left hand to a lower note. Lets do a pull off from the 2nd fret 5th string to the open 5th string.

Use the tip of the finger and pluck the string by pulling down towards the string below it. Try this on all six strings.

You can combine hammer ons and pull offs as well. Here is a combination hammer on, pull off in the same spot.

You can also play this as a continuous lick, which then becomes a trill.
Warm Up and Drills by Peter Vogl is a downloadable Quicktime video lesson focusing on guitar specific stretches, drills, and excercises. These guitar techniques will help you become a faster and more accurate guitar player, help prevent pain associated with playing the guitar, and get you prepared to play. The exercises included in the video will help you improve vital guitar techniques like picking speed and accuracy as well as left hand dexterity and reach. $4.99