Do i have to finish my whole manga story and do the comic or i should just finish a manga chapter and do the comic? Help me please!

You need to get drunk and smoke some weed.

What is this I don't even

I'd say which ever is more convenient for you. If you don't want to draw the whole entire story at once, then I suggest doing something like a chapter or two and catch up on the drawings. I personally would want to just do a little writing, then drawing, but really its whatever suits you better.

This. It's really just personal preference. Do whatever motivates you at the moment. If you want to draw, then draw. If you want to write up, then write. Just be aware that you should at least flesh out the story first before you start drawing or else you'll repeatedly be going back and redoing pages and panels.