How to raise drop bars to a higher position?

Hi I've been cycling for a little less than a year now and I'm so much in love with it that I ride my bicycle everywhere I can pretty much get to. I started off with an Ozone 500 (one of those academy bikes). Then I got my first Giant. I don't know what model exactly but I will tell you it isn't a super high end Giant. The Giant felt so comfortable and I only use it for working out (for obvious reasons I don't want it to get stolen). I still use the Ozone for city usage, meeting friends, and ECT. But now i have gotten so used to the Giant that I notice I get back aches mainly because the drop bars are lower than on the Giant. I've learned lots of maintence tricks but I am unsure how to raise the drop bars. Could somebody please explain how I would do this if it is even possible? I think 2-4 inches will solve my problem. I do not want to switch to flat bars because on those windy days I remember why I switched to drops in the first place. Thank you!