You need to learn basic grammar and spelling before attempting to become a writer.
A writer, yes. However to publish a book, no. Although it wouldn't hurt, as my spelling has always been horrible, and my grammar not too far behind. However my desire to tell a story far outweighs those two deficiencies and will make those but small hills.
One thing I know would help is to read more. Unfortunately I fear reading. As a person always coming up with stories, creating characters, and so forth, it is hard for me to be original when surrounded by so many sources. I may, for example, take someone else's writing style, which ultimately I would rather forge my own.
Interestingly, I can watch movies without them clobbering my thoughts for weeks on end, but again, this is not the case with novels. When I read a novel I get way too into it and that becomes the center of my thoughts for some time.
So admittedly the only book I have ever read is that which has been assigned to me in a class! And now here I am, trying to write a novel, and ofcourse the lack of experiance shows. So what do I do? Try to get enough of a style down, and enough of the plot/characters fleshed out that I can then go through and refine it as my skills develop. I feel if I do this the other way around, I won't have an original piece of work, and it won't be my piece of work. As is I am walking on egg shells writing in the fantasy novel genre.