hold the "note on" buttons while moving the sliders to adjust the start and end points. the left slider moves the start point, the right one moves the end point.
unfortunately end points don't work the same way as the 2000xl. the 2000xl was nice because the more you moved the data wheel, the more the end points moved, and if you slowed down, it would move the end points slower as well.
for some reason they got rid of that functionality (stupid move in my opinion and hopefully it gets brought back), and what you have to do is hold shift and click the left cursor button. doing that will select the tens column, and so every click of the data wheel will move the end points by 10. hold shift and click the left cursor button again and you'll see that the hundreds column is selected and each click of the data wheel will move the end points by 100. hold shift and click the right cursor button and you'll be able to move by 10 again.
there's no zone feature like there was on the 2000xl. it's been replaced with chop shop, but i never used the zone feature on the 2000xl nor do i use chop shop so i can't tell you the difference really.
i think the 2500 is very similar to the 2000xl, but there are a few minor changes. the best advice i can give is to read up on everything you're not sure of in the manual. not only will you learn the machine, but it will save you the sarcastic and bitter responses on this board when you ask a simple question that someone may think is a waste of time.
p.s. the end points was the first thing that i wasn't sure of as well when i switched over. another thing i found out was you can't convert a sample from stereo to two mono samples in the 2500, you have to resample to do that. not too much that i couldn't figure out on my own own though without a little trial and error or a trip to the manual.