Did you look for help with how to learn sign language or did you look for help with how to sign "how"? Here is both!
There are several sign; few of them were used in old times.
Definition: In what way or manner; by what means; used to ask about the condition or quality of something.
Pronunciation/articulation: Dominant "10" handshape (palm orientation facing left) twisting once while in contact with passive "10" handshape.
Variation.
Pronunciation/articulation: Dominant "10" handshape (palm orientation facing left) twisting twice while in contact with passive "10" handshape.
Old variation; still used today in the 21st century but less used.
Pronunciation/articulation: The tip of the dominant "15" handshape twisting while in contact with the tip of the passive "15" handshape.
Another old variation; still used today in the 21st century but less used.
Pronunciation/articulation: Both 15-handshape (palm orientation facing signer) hands in contact twisting forward.
Related signs: how many, how much.
Other WH-Questions: WHAT, WHICH, WHERE, WHEN, WHY, WHO.
Sentence example: HOW YOU? for "How are you?"
First 100 words.
As you feel more comfortable with the first few hundreds of ASL signs, progress further with your vocabulary and learn signing more.