Congrats on your weight loss! That is wonderful!
My sister broke her back a few years ago and just lost all of her muscle and strength. Once she recovered and was cleared by her doctor, I got her Cathe's Beginner/Intermediate series called Low Impact Step/ Total Body Sculpting and there was a stretch dvd that went with it. This helped her inch her way back into getting in decent shape and she progressed from there. Note, she started with the stretch dvd which I think is an awesome rout. I'm recovering from a shoulder/collar bone injury and I've been doing yoga and I feel that it has kept me well conditioned just by working on flexibility and staying within my restrictions set by my dr.
STS can be started by a beginner but I think you would find the workout I recommended to be less of an investment and would do a great job at getting you started. Also, you can make any workout as easy or as hard as you want based on the wts you use and how hard you push yourself. I would build the foundation gradually so that you don't get discouraged and I feel it would be less painful. If, you opt for the 2nd meso cycle you should listen to your body.Cathe designed the program so that you are using the proper wts that your body can handle. That is what the 1RPM is all about. I would strongly recommend completing those before beginning the program.
Just my .02
~Reece~