Please help me with this workout thing!!!?

So im 5'4 and 142 lbs so not fat just a lil chub on me from baby weight. blah. anyways i want to lose 20 lbs. ive been going to the gym and working out my arms, shoulders, back, and chest one day and then my legs, claves, butt, abs and cardio the next then i switch back and forth. i dont do very much weight because i want to get cut and not gain a lot of muscle. Im usually there working out for an hour and a half to 2 hours and i was going every day then i stopped but how long do i have to be there to effectively lose weight and lose 20 lbs? and how long does it take to lost 20 lbs at that rate with the work outs im doing???? PLease help im not the best with this stuff! thanks!! and any advice is appreciated! =)