The word 어떻다 is rarely used as 어떻다 in sentences. Actually, if you asked Korean people if they thought that '어떻다' and 어떻게' are the same word, they would probably say that the two are completely different words.
In addition to 어떻게, there is another way that you can use 어떻다 in sentences. Through conjugation, 어떻다 can change to '어때." I'll show you how 어떻다 changes to 어때, but you really don't need to worry about how it is changed (there are only a few other words in Korean that can take on a similar transformation).
1. 어떻다 is an adjective
2. ~아/어하다 can be added to some adjectives (You already know about 좋다 + ~아/어하다 = 좋아하다)
3. The addition of ~아/어하다 causes the ㅎ to drop (you will learn more about this later)
4. 어떠하다 can conjugate to 어떠해
5. Say 어떠해 fast enough and it comes out as "어때"어때 is used to say "how is/was the...?" or "what do/did you think about...?" It is used when you want to ask somebody's opinion/evaluation of something. It sounds more natural in Korean for the thing you are asking about with "어때" to not have a particle. For example:
남자 친구 어때? - How is your boyfriend? (is he good/bad/handsome/etc..?)
It is also very commonly used in the present tense to say "how about... ?/what do you think of...?" For example:
점심 어때? - How about lunch? / What do you think about lunch?
Think of this example. You and I are searching through a bunch of pictures, trying to find the best one for my profile picture on Instagram. I find one that I like, but I want to ask you "what do you think about this picture/how about this picture?" In that case, I can say:
이 사진(이) 어때? - How about this picture?
In fact, 어때 is probably the most commonly miss-translated word by Korean speakers learning English. If you ask a Korean person what '어때' means, they will all say it means "how about." Sometimes, this is true, but 어때 can only be used as "how about" in a limited number of cases. In the example I just gave about choosing a good picture, 어때 can be translated to "how about." But what about in example with the boyfriend?:
How about your boyfriend?
Sounds weird, and most English-speaking people probably couldn't even understand the meaning of this sentence.
Try it sometime. If you have a Korean friend (one that can't speak 100% perfect English), ask him how to say "한국 어때?" in English. I guarantee he will say "How about Korea?" But really, this should be translated to "what do you think about Korea?/How is Korea?"
~요 can be added to 어때 to make it more formal. Also, 어때 can be put into the past-tense to ask about something in the past. But note that even if you are asking about the past, it is not 100% necessary to use 어때 in the past tense:
시험 어땠어요? - How was the exam?/What did you think about the exam? (was it hard/easy?)
점심 어땠어요? - How was the lunch?/What did you think about the lunch? (was it delicious?)

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LEARN KOREAN (한국어) [GRAMMAR] #1
RandomThis is book #1 for the Korean Language series. Try to understand all of the notes in this book before you proceed to the next one. Good luck ! This book contains Korean grammar. Try to understand it so that you can understand how to make a sentence...