"How are you?"
That's a quite complex question, but I hope this helps to get an overview:
For the beginning probably it’s good to know that verb structure in Swahili is somehow built like a train: There are many wagons on the train and every wagon has it’s own slot. If possible, you can leave out some wagons, but you can never change the order.
So to build a verb basically you take the wagons for subject, tense, (object) and word stem:
SUBJ. - TENSE - (OBJ.) - STEM.
ni -na - (ku) - penda
-> nina(ku)penda = I love (you)
That’s how it works basically, but there are much more slots for other wagons in the train of Swahili verbs. (Possibly you can spot the structure somehow in the greetings, but they are so strongly conventionalized, you cannot always apply the common rules to those phrases.)
Secondly you should be aware of „concordance“. One could say there are 15 grammatical genders, but you rather talk about noun classes that categorize nouns mostly due to semantic criteria. The head of the phrase determines to which noun class you have to adapt other relating words and grammatical affixes.
Juma alikisoma kitabu.
Juma a - li -ki - soma ki-tabu
Juma 3SG- PRÄT - cl7 -read cl7-book
= Juma read a book.
Kitabu (book) is in noun class 7 (like most "things"), so the object concordant within the verb has to correlate with class 7 (-ki-).