Why does joha spell as 좋아 but not 조하? what is the different? don't they sounds the same?
Yes i am beginner. Today is my second day actually learning properly. I will eventually look for tutor in a month or so after i learn basic characters fluently. ^^

Question

Answer

According to the rules of Korean orthography(한글맞춤법)

Article 15, stem and suffix of the predicate(verb or adjective) should be written separately.
제15항 용언의 어간과 어미는 구별하여 적는다.

ex)
in 먹다, 먹 is stem and 다 is suffix
먹다
먹고
먹어
먹으니

in 좋다, 좋 is stem and 다 is suffix
in 좋아, 좋 is stem and 아 is suffix

좋다
좋고
좋아
좋으니

Answer

First, wean yourself off of romanization as quickly as possible. Second, it's part of the more advanced (not really advanced) pronunciation/sound change rules. There's a whole list of them here: https://en.wikibooks.org/wiki/Korean/Advanced_Pronunciation_Rules ㅎ before ㅇ is silent. The sound does not carry over. Besides, ㅎ in the final position has a "t" sound, not an "h" sound, so it wouldn't make sense for the "h" sound to be in the next syllable anyway :)

Answer

I think this video may help you.

https://youtu.be/1bQvXTLMTwI 
- Pronunciation of 좋아요