"Qué tan" significa "cuán," hasta qué punto. En inglés sería algo como "how much". No tiene nada que ver con "como"

I just can add that the best way is to read you will get a level where you just simply know where to use whatever. 

i'm not so good in english so sorry if you can't understad me. ''¿Qué tan?'' i use that to give one level of category, like... When you wanna know the size of something and you asking if is bigger o middle and you triying to know if is good to you. Or to know the price of something with the how much. The ''Como'' is like how. (Como, in question needs the little point up the 'O'; ¿Cómo estas?

I hope you can understand the point :)¨

¿Cómo? Is used to ask about how do you something. E.g How do you pronunce Rhythm? ¿Cómo pronuncias ritmo? Also have another uses.