Pitch Shifting Sounds
You can change a sound's pitch by clicking the Sound Details Tab on the bottom of the window.   If you want the sound to obey key changes on the time line or be relative to the project's key, you should look into setting the key of the sound.

Do Not Fix Pitch
If you don't care about changing the sound's pitch, you can choose Do Not Fix Pitch on the Sound Details TabIf you are time stretching the sound, the pitch will be altered by the same percentage as the time stretch.

Adjust Pitch By
Choose Adjust Pitch By from the drop down list on the Sound Details Tab.

This allows you to change the pitch by semitones.  You can type in a partial amount such as 1.26 semitones or use the drop down or spin arrows to adjust by a whole semitone or 1/10th of a semitone.  You might use this option to fix a slightly off key vocal performance or transpose a sound into a key you are more familiar with.

Adjust To Project Key
Click here for more on adjusting a sound's key.