How to become a tell a marketer?
Do you have to go to college?
Do you have to take classes?
Some companies may provide training, having the right personality and disposition may be more important than a degree, the experience doing this un-thankful job can condition you to better deal with people and being rejected in more important sales jobs.
You might find ads on classified ads sites like Craigslist.org or offers in freelance marketplaces like odesk.com or freeelancer.com