Help on starting combos

Hey guys, beginner here. Started playing less than a month ago on PS4, using controller. I've been struggling a lot to do combos but I'm starting to be able to accomplish them, at least on training.

My problem is, now that I've reached super bronze, my opponents aren't dumb enough to simply let me jump on them and start a combo with HP. It simply won't happen. They don't really anti air much, but they block, so jumping in with HP or HK seems completely useless. However, that's how most combos start, at least the ones listed on challenges. (I'm talking mainly about Ryu and Ken here, the ones I play so far).

I know good players usually don't jump a lot and start with stuff like cr. LP or MP and then somehow connect into more damaging combos, but that simply doesn't seem to work for me. Even when I manage to successfully land a cr. MP or MK I'm not able to follow it up with anything, mostly because of the distance between the opponent and me. What am I doing wrong here?