First off, congrats on at least (I'm not sure what you're doing or how you feel, but you are in a thread about fitness, so that could be a start!) being interested in improving your life!
No shame in not being able to do a push up, or a squat! Many people (especially women) are in the same boat, and all it takes is a little time and effort, and you can get there!
You mentioned you're obese, but since I don't know your age, weight, medical situation, etc. it's hard to give specific advice, but I would definitely recommend first checking out the way you eat, exercise can come later (if you want.)
I would definitely suggest checking out /r/loseit.
I have to admit, I'm a tad biased since I'm currently on the keto diet, but it has certainly worked for me, and many others. You have a variety of options, but if you're interested, the folks over at /r/keto are very helpful, informative, and encouraging! If you have any questions or are nervous, feel free to message me and I'll answer any questions I can!