am i too obese to be doing weights

You are never too obese to do weights everyone should do them

For real starters to building some muscle - I would suggest Convict Conditioning - it's a book by Paul Wade and his program really starts from scratch.

Eg instead of full pushups, you can start doing push-ups standing with your hands against a wall and you do a "push-up" against the wall. Really good for starters - and gradually you move upwards, the goal is doing even one hand pushups! It takes time, though and this time can be used as a "therapy" to either lose weight or heal old injuries..

Of course, there are pullups, squats, leg raises etc done in a similar fashion.

Fingers crossed, you can do it!