Search online for publishing houses. Look for companies that specialize in comic books. Carefully review their requirements for proposal submissions. Bookmark the listing or make a list of what you will need to include in your submission.
Assemble your proposal. Include a sample of the what you think are the most compelling pages of your book. Type up a summary of your story and a query letter, an introductory letter that explains who you are, why you think your story would be a good fit and any past credits you have.
Place the proposal in a manila envelope with a self-addressed stamped envelope; companies typically won't respond to you if it takes unnecessary time and expense. Mail it to the publishing company through standard mail.
Respond promptly to any interested response in your book. Oblige any requests the company makes for more information about your book. Inquire about any necessary deadlines before publication.