Deepest sympathy to you and your family. You have been doing an awesome job on your weight loss though! Congratulations on your continuing success and way to get yourself into a lifting program! For beginners, it might take awhile to figure out the amount of weight you should be lifting for each exercise. You'll be able to get feedback in 2 ways: 1) while you're lifting and 2) your level of soreness the day after you lift. You should for sure try incrementally heavier weights while you're at the gym if the moves you're doing feel too easy. You should for sure use a lighter weight if you can't complete more than 6 reps or if you feel any kind of joint pain. Then evaluate your soreness the next day or 2 days after your workout. You want your body to be pleasantly sore - a level that means you worked your body hard, but that you still feel motivated to go to the gym again soon. If you're not sore at all the next day, that means you didn't lift heavy enough :-P If you're sore for 3 or 4 days, that means you pushed too hard and should probably back off on some of the weights. The New Rules for Lifting for Women is a great program for all fitness and experience levels. Good luck!

So terribly sorry for the loss of your precious daughter. I am inspired by your courage to improve your health and well-being, even after going through what you've been through. You are doing a fantastic job. Yes, I agree with the others' advice to follow a progressive, regimented lifting program such as Stronglifts 5x5, New Rules of Lifting for Women, etc. There is actually a group here on MFP for ladies on the Stronglifts 5x5 program which has lots of information. I started the program about 8 months ago and have noticed a nice gain in strength and even my ability to run and bike more efficiently. Feel free to friend me if you have any questions! Take care.

First off - you are an inspiration. And I second everything @modmom1‌ said.