There are plenty of places that will advertise to find a job for you; placement agencies, temp agencies, and others like that, but those places usually will spend the majority of their time working with people with skills and experience before they will even look at someone who is just beginning.
There are also sites and blogs that will advocate the idea of doing work around the neighborhood; mowing lawns, cleaning houses, walking dogs, babysitting kids, etc. There is nothing wrong with this kind of work if you can get it, but you also want to make sure you are doing an appropriate amount of work for the money you will be getting paid. I don’t know how it is in other parts of the country, but in California, I would never recommend for a teen to try and compete in the lawn mowing game. There are too many people who have their own equipment, trucks, and large numbers of unskilled workers who are willing to do the job for less than you could afford to. Babysitting is fine, but again, you may wind up competing with people who have more skills or experience to do the job.
In the earlier instances, all of these jobs also share the entrepreneurial spirit of working for one’s self, and not for the other guy. If you have that spirit, are willing to put in a lot of hard work, and have a plan, good luck! If, you are like most of the rest of us, you need to work for someone else. There is a reason teenagers have a reputation about being lazy and unwilling to work. I don’t say that this is a true representation for all teenagers, but I think we all need to admit there is some truth.
That leaves only a couple of other options for most of us to get a job. Either the local mall or shopping center, or, and I’m sure we all know who I’m talking about here, getting a McJob.