The rightmost pedal is the sustain pedal. Pressing it lifts every damper at once, so notes already played keep sounding and the undamped strings ring in sympathy. Its job is to connect sound, not to make it louder.
A piano usually has three pedals. Right to left: sustain (much the most used — almost every pedal marking means this one), the middle pedal (sostenuto or a practice mute, depending on the instrument), and the left una corda pedal, which makes the tone softer rather than simply quieter. Early on you only use the right one.
The technique that matters is called syncopated or legato pedaling: when the harmony changes, play the new notes first, then lift the foot and immediately put it back down. Hands first, foot second. Move them together and the previous chord gets dragged into the new one, which is the muddy sound.
Marking
Means
Ped.
Press here
✱ (star)
Release here
A bracketed line
Hold across this span; a V notch is a pedal change
sim.
Carry on the same way without further marking
The foot stays quiet. Heel on the floor, only the ball of the foot moving, and the foot never leaves the pedal surface — letting it snap up produces an audible clunk. Fully down and halfway down are different effects; half pedaling comes later.
Common questions
What is a sustain pedal?
It is the rightmost pedal of a piano, worked by the right foot, and on a digital piano a foot switch does the same job. While it is down, notes keep ringing and fade away on their own after you let go of the keys.
What do Ped. and ✱ mean?
Ped. marks the moment to press the pedal and ✱ the moment to let it up. A line with a V-shaped notch asks you to lift and press again at that spot.
When do you change the pedal?
When the chord changes, not at every barline. Play the new notes, then lift and press again, so the old harmony does not bleed into the new one.