Improvement in karate comes from repetition, honing and muscle memory.  You can go, once, twice, 3 times a week, it doesn't matter that much.  More is better, but most important is the regular schedule. Do the warming up exercises/stretches and cooling down exercises at the beginning and end of each practice.  Not only are they good for you, but all the stretches allow you to become flexible enough to learn more advanced techniques. There is a lot to learn, but just take it one at a time.   Kihon means basic training.  Most classes will start with some Kihon to get into the swing of things.  Since karate is learned by muscle memory, repeating basics is helpful (and fun.)  It includes basic punches, kicks, blocks, and stances. "Kumite" means, "sparring."  In almost all schools, beginning sparring is structured, with no contact allowed.  As you progress, you get to more and more free forms until you are doing free sparring. "Kata" means "prearranged exercises/Form."   Kata's consist of between 8 and 72 choreographed moves, where you can show your skill in front of others.  Katas will be different in the different styles of karate. Mostly, they consist of kata and kumite contests.  By seeing other schools compete, you will learn a lot about the strengths and weaknesses of your school. There are tests occasionally, where you can show your stuff and get a great new colored belt.  Although you barely can find this American System its well known and practiced in Western and Middle-East societies. Normally, the instructors only let you take the test if you can pass it.

TL;DR in Indonesian:
Tentukan jumlah hari dalam seminggu untuk jadwal latihan karate Anda. Nikmati pemanasan. Berlatihlah dalam berbagai bagian karate. Ikuti berbagai turnamen. Raihlah tingkat sabuk yang lebih tinggi seiring perkembangan Anda.