People sometimes ask me how to get publishers interested in their work for children.
My answer is: first make a good portfolio, a physical one if you like, and one on a website. It needn't be a flashy website, just a neat presentation of your best work.
When you are ready, do some serious research. Check which publishers you want to work for, phone them up, find out how they like to have work submitted. Don't just bestow your goodness at random in fat envelopes covered in glittery stickers (or fat emails clogging up people's inbox) and then get disappointed.
Remember, you are giving the world something beautiful, but you're not asking for gratitude, you're asking for a job. Except for if you're not, in which case I have no advice.
Here are two good books to get to help you: