Okay so here's what I think you should do:
First go outside, and start your warm up, either use your street or a nearby park.
I want you to do some static AND dynamic stretching (give it a google search if you're unsure of the difference), and then start the main part of your warm up and do some sprints. I'm not an expert on sprinting, so I'm going to say sprint say 30 meters ten times (that's what I was doing in my early sessions with a personal trainer), then it's time to begin your kicking drills.
Kicking full power in shadowboxing can be a little risky, you might twist your knee or fall over and hurt yourself. So I'd recommend doing the drills in this video that do not rely on the bag:
This is not about kicking hard so much as it is about kicking with fluidity and being able to kick both on the front and back foot. Which is very important.
Then once you're done with that work on your shadow boxing, specifically focus on your punches and make sure they're balanced, make sure you get your hip and shoulder back as far as reasonably possible to get maximum weight transference (I'm not an expert on this front but
@Sano will likely be more help)
Then after that it's time to begin your physical work out routine, this is the bit that you'll probably want to skip but really shouldn't as it's going to build your muscles to be able to explode into your punches and kicks.
Four sets of 10 clapping push ups (go all the way down and explode up, don't half ass it, if you find it difficult then make do less sets)
Four sets of 10 dumbell lunges (if you don't have dumbbells and don't have access to a gym, then either buy the dumbbells when you have money free or do them without weight)
Four sets of 10 single leg squat (each side, if its too much then halve the amount of sets)
Four sets of 10 dumbell squats
Four sets of 10 deadlifts
and finally four sets of 10 jumping squats.
If you're new this is going to suck and you may feel a bit sick after, but it's nothing to panic about, make sure you get something to eat straight away after, it's not a bad idea to prep some chicken or a protein shake before doing this workout so that its on hand ready.
I'm not claiming that this will make you hit like George Foreman, but it will certainly increase your power.