Hi,
Firstly, if you really wanna learn how to jump it might be worth looking at a slightly bigger kite (you'll need bloody good wind to get airborne with a 3m!), I dunno how experienced you are but it might be worth giving a blade 4.9 or 6.6 a go (there's quite a few on ebay at the mo ) and I can certainly vouch for blades (having owned a blade 4 4.9 for about a year and a blade 3 8.5 for about three years). As far as technique is concerned, follow what the guys said above (I think that's pretty much how I do it anyways), however just remember the higher you keep the kite in the window as you move it across the window the higher you will go (generally speaking and only to a certain extent, take it too high and there won't be enough power), also the higher in the window the easier the landing should be. As a further note the bigger kites are much better for bigger, smoother, more controlled jumps whereas smaller kites tend to knock you about a bit , on the reverse however smaller kites are much easier to fly for longer periods and are generally easier to maneuver and learn with. The best thing you can do is just go out and try it, (all the above is speaking from my own experience and so won't necessarily be correct but hey, give it a go, you'll know when you get it right!),
Sorry for going on a bit,
and good luck!
Kieran