Firming up the bottom half?

I'm almost 5 months out and all I've done in the area of exercise is some walking, which by the way, I've slacked on over the last couple of weeks.  I'm scheduling myself to join the YMCA very soon so that I can use the resistance machines and the stair climber.  I'm most interested in doing some type of regimine that will tighten and tone my body...especially the lower half.  I want firmer thighs and glutes.

Is there a simple at home routine that I can do that may work? 

Congrats on fighting to win the battle of obesity and better health. I would suggest meeting with the YMCA's fitness director. Most YMCA have someone on staff to show you how to properly use their equipment. You can then use hand held weights at home. I would suggest keeping your cardio workout fun and exciting. Do whatever is fun to you. You really have to get in the mindset that this is a lifestyle change for a lifetime. We often make one plan and get bored with it. I personally do most of my workouts at the YMCA and run outdoors. If I bought all kinds of stuff to use at home, I end up finding a million other things at home I should be doing instead. I do better when I plan my workouts and go to it rather than adding something to do at home on top of all the stuff I need to do at home.

I don't like when people sugar coat things so I won't do it either. I weighed 190 lbs. (5 6") and my weight now is between 125-129 lbs. I've been running constantly for over a year now (training for a marathon now) and my thighs and tummy are still a mess. However, they have improved, but without plastic surgery I will never have the legs and tummy I once did before become overweight. I think in my mind I thought I would snap back and be fine. It just doesn't always work out like that when you've lost that much weight. The reason I bring this up is don't make your goal so hard to reach. Be realistic with yourself. Don't shoot for Halle Berry's body or a certain number on the scale. Make small goals you can easily reach and then increase it in small steps. Just keep moving and make it fun. Your life will improve if you can pull that off. Best wishes to you!