How can I best improve my fitness?

I am 15 years old, about 5’9 and weigh about 130lbs. I’ve recently got some dumbells and have started doing home abs exercises which I found on youtube - http://funadvice.com/r/3k3fhgs6ih

I’ve also started jogging a bit, but not very often or challenging.

I am starting some martial arts soon (most likely jujutsu), and I’m looking to improve my all round fitness and stamina, but specifically I want to get stronger arms as well as stronger abs and of course eventually a six-pack.

So far, I’ve basically been doing as many bicep curls as I can, with two 2.5kg weights on the dumbell, but recently I’ve heard that this isn’t actually the best way to increase strength.

As for abs, I’ve been doing the workout in the video every two days and have noticed little visual effect, even though I am in no way overweight. However I imagine that if I jog more often I will see more results?

I don’t know much about the differences between muscle tone, hypertrophy etc., but probably the best example of the perfect physique that I aim to get is that of a free-runner - athletic, not freakishly strong, but able to lift my own body weight and look muscular without looking freakishly strong like a bodybuilder. An example of a free-runner’s strength is the ability to perform the “parkour flag”, when you grab onto a vertical object like a lampost and hold your body up horizontally. I’m going to get into free-running as well soon, at which point I will start jogging more regularly and seriously as well.

I think that this kind of physique looks good, and will also be a good physique for martial arts - correct me if I’m wrong.

Given all that I aim for, what is the best work-out programme for me? Is what I’m doing now fine? Sorry for writing so much, I’m just trying to give as much information as I can. Thanks for reading, I greatly appreciate any advice given :) ?