If your back is a problem area than avoid standing exercise for now. Sitting down is Ok for a begin. You can use a bench or a chair.

A back exercise could be good for you. The muscle will protect your back and make other exercises possible.

For example: Start with 'Rows' on a chair. At first without weight until the total movement is comfortable for you body. Take a couple of weeks. Then use a small dumbbell. Take especially care not to go beyond your 'no-pain' range of movement. Exercise only once a week. Do ALL movements slow. Also every movement you make around the exercise itself.

Also a simple squat would be good, same pattern as before. The most simple begin of a movement is OK. This will train a core of stability for your whole body.

However small this start has to be: muscle will start growing, movement will enhance.

However unbelievable it seems, with once a week and only a couple of reps and no or little weight, in time you will get better and better. The tric is that your body itself in the resting period will enhance and build muscle etc. You yourself will grow in confidence about movement and training. The in time added muscle will help burn fat and make you look better...

Look at video's of Row and Squat to familiarize with it. However small your start is, take it serious in your approach.

Happy exercise Carrottop!