"spinning" can be both pedaling at a high cadence(rpm) or indoor cycling on a specail bicycle. Depends on context, which sound like high-rpm pedaling (at least to me)
If I remember , going at an easier rate(i.e., the 60-70 that Bad Ju Ju mentioned) than all out, will actually burn a high amount of fat. A lot of people will refer to this as LSD training.(Long Steady Distance).
As every one else has pointed out, be patient. You didn't put all the wieght on overnight, so it's not going to come off overnight, either. I lost over 100 pound via cycling, but it took me over a year to do it.