Can I advertise on Craig's List for a doggy day care service? Is it free?

I'm hoping to start a small business and I need to advertise wherever I can! I'm not too familiar with Craig's List but have heard good things about it. Where else could I advertise? I've thought of making brochures but want to see if I get any responses before investing. In the meantime, I can make some good fliers on my printer. I was thinking of advertising at pet stores, grocery stores, post offices, libraries, vets, etc...? Can you think of anywhere else? Thanks for any ideas and info. about Craig's List!