Don't get too bogged down with reading books on writing. The best way to learn to write is simply write. I have read numerous books on writing in its various forms, and they all pretty much say the same thing over and over and over again. There is no magic to writing. You just have to do it. If you want to write for comics, then get your hands on some actual comic scripts and analyze how those writers crafted their stories. You can find some here: The Comic Script Archive. And don't worry about the script format, it's really not that important until you find a publisher, and they'll advise you of the format you should use.
For now, just write. Write about anything and everything. Write short stories, poems, haiku, screenplays, non-fiction, essays and, of course, comic scripts. Don't worry if you don't publish right away, I've got a small collection of rejection letters for shorts that I have written. And here's a funny haiku that I wrote for an esoteric haiku magazine sometime ago. They rejected it, I can only wonder why:
She wore a red mask.
It did not hide her face well.
I drank much whiskey.