changing the tempo of the sample after it's sampled

I just recently purchased the mpc2000xl and I figured out how to sample, but I can not figre out how to change the tempo of the sample after it's been sample and located into one of the pads. In some cases I might want to speed the sample tempo up or slow it down to match other sampled material.

in the program screen mess with the tuning, it also messes around with the pitch at the same time though. Since you got an XL you can also timestretch it.