>>71954
Kinda depends on how much time you have. There's no quick way to doing it and everyone is different. Whatever you want to do you have to approach it with balance. If you have no equipment, you can do pushups, situps, pullups and squats. Do the latter on a seperate day. For each of these, especially with squats you want to push yourself. Unless you're completely sedentary your legs are probably a whole heck of a lot stronger than you give them credit for.
Mountain climbers and running are good for building up a sweat, do these on the days you don't do squats or you're going to be harshing on your legs.
As for diet, it depends on what your goals are. If you can cut back calorically you'll lose weight. Things like pop and fast food are horrible for your diet because they have an excess of sugars, salts and oils, to keep it simple. They're also the most common dietary vices. The more you can cut down on these the better. I'd recommend trying to make simple, attainable changes, before trying to go full Spartan warrior mode as you'll like get burnt out and just end up despondent.
From there if you want to get more serious, I'd recommend checking out the /fit/ boards of 4chan, 8chan, and 7chan. They should have some cumulative amount of resources to at least point you in the right direction to get some better information or give you an idea ultimately of what your ultimate goal will be.
There's a board here >>>/ath/ that has some good write-ups on the science behind building muscle. But the important things to me are always mental, like you said you need a solid regiment, espcially when you're starting out that you can at the very least maintain, so it needs to be realistic.