Slapping is a bass technique where you hitting the string with your thumb near the start of the neck, often pulling or snapping the higher strings with your index and middle finger (popping). This technique first appeared in the 1970s and was synonymous with the funk music of that period. Larry Graham, bassist with Sly and the Family Stone, was one of the bass slapping pioneers. The eighties saw a new generation of slappers, like Mark King of Level 42.
This is a useful instructional video for absolute beginners on the guitar. Jeff Isbell shows how to play the basic open chord shapes, E-A-D-G-C. Jeff gives a few fingering alternatives for the basic shapes.
Palm muting is a common technique in rock guitar playing. Resting the side of your palm on the guitar bridge gives a percussive quality to distorted chords. The trick is using just the right amount of palm pressure: too much and you wont get any sound, too little and you will loose the chunkiness.
Have a look at this video from Gary Schutt . Gary has a degree in songwriting from the Berklee College of Music and has written over 150 songs, has 5 CD's, and 1 DVD currently available.