Try to set youself a daily routine, where you eat at set times, (doesn't have to be exact but near enough the same times daily). Take it easy with exercise at first, be gentle with your body. Everyother day do some light exercises, start off with small amount and increase it as it gets more comfortable, try things like bicep curls using just your arms ( no weights), side to side steps, take a 15 minute walk, jog/run for a small time in your home (on the spot) set a timer on your phone for say 20 seconds and try to run for that time or even walk on the spot increase the times as it gets easier.
As for your overall diet as others have said plenty of fruits and vegetables, the key is to try to make each meal contain a source of protein(meat/fish or meat susbstitute), some fibre ( things like oatmeal/porridge wholemeal bread products. skins on potatoes, easily found in other vegetables and fruits). Unless you can go complete cold turkey on your snacking try to replace unhealthy snacks (like chocolate bars) with a piece of fruit, (crisps/chips(if american) with nuts), and if you enjoy chocolate try to top fight high % cocoa as it will contain less sugars, but if you still want the low % cocoa high sugar, try to cut it into pieces and opt for 1 or 2 pieces a time instead of a whole bar.
Remember it's a journey not a race.