I was in your situation when I was 14. I'd suggest that you focus on being active. Bike, skateboard, hike or walk, shoot some hoops every day. These activities burn calories and develop overall fitness. Supplement with some pushups, pull ups and sit ups. Don't wory about how many you can do today, focus on doing more reps each time. If you can do 10 push ups your goal is to do 11, then 12 then 13...Good luck and remember the key is to make it fun.
This is what I was thinking as soon as I read the title. Don't worry so much about getting into a lifting program right now, not unless you have some major athletic goals in mind lying ahead. Just be more active. Play sports. And don't specialize in one sport. The top dogs know that this is not a good idea.
I will second focusing on more reps and add to focus on form also. If you're only going to do body weight work (not a bad thing), here's a list of good exercises:
Prisoner squat
Lunges
Planks/Side Planks
Reverse Crunches
Pushup variations (close grip, wide grip, regular)
Pull ups*
Chin ups*
Inverted Rows (if at all possible)
SL Calf Raises
Assisted Handstand Pushups (look up handstand pushup; assisted would be putting your feet on a chair and getting into a "pike" position, then doing it)
*You'll need a pull up bar for those.
Look those up on youtube if you need. If you don't understand, come back with questions. I'll be happy to help
I'm going out on a limb here but judging by the user name and "gamer nerd," you're a male? If that's the case, you do NOT need to lose a lot of weight. Especially are your age. You'll be very unhealthy if you do. You're pretty much right where you want to be. You just need to change your eating and exercise habits. Notice is first; that's because it's more important