Well, there's no real way to teach someone to draw manga, that comes from practice, research, and experience. I am an artist and would love to help out but that's not possible over text. But here's this,
Look up manga tutorials on YT along with comic format drawing, character design, profile drawing (you'll be drawing lots of faces if you draw manga), background and landscape drawing, and if it'll be colored, you'll need color theory, if not colored, you need to learn shading and the use and technique of cross-hatching (the criss-cross lines used to shade in manga).
Now, this will also all depend on if this will be a traditionally hand drawn manga, or a digitally drawn manga. If it's digital, you'll need a good program (a good program isn't an expensive one, its one you understand and feel most comfortable using), good understanding of using the new tools at your disposal, and learn how to create traditional (on paper) looking drawings in digital format.
If it's traditional, you don't need many tools, just get a large mixed media sketch book, a set of H and B pencils, a good eraser (the ones that you can mold like clay are the best because you can make them very small and erase small details), definitely more than one sharpener (go for the more expensive ones, cheap is cheap for a reason), and a set of different shaped rulers, having curved and natural angle rulers will help a lot.
And most importantly: if you feel like you can't do it or it's not working out the way you wanted, don't give up, but don't pressure yourself either, it'll take time to master the manga format, just have fun and have at it.
