Vegas has lots of little tricks to perform pitch changes in an audio track.

Try selecting the waveform (just click) and press the "[" or "]" buttons to change the pitch (depends on your keyboard shortcuts, may be + and -).

Or, right click on the wave form and explore the properties option, which allows you to change length and pitch.

Finally, if you have selected "Lock to stretch" in your properties tab, you can hold down Crtl and drag the end of your clip around, this will squish or stretch your audio and make it’s pitch change.

Hope this helps, if you are still unclear, drop me a note and I’ll give you some more tips. (Also, Vegas help is VERY useful and easy to understand.)