i don't see anything wrong with younger people posting on this board to gather information about future careers and whatnot. message boards can be a resource just as much as going to the career center at school or whatever.
as a senior in college, you network as much as you can by going to career fairs, trying to get research and internships with companies you are interested in jobs with, and fill out applications and do interviews with different organizations until you get hired somewhere. usually colleges are very helpful in organizing career gatherings and notifying you of internship and research availabilities (at least my university was). a small (very small) percentage of college graduates may attempt to open their own business and a few are even successful in that.
as a senior or resident in dental school, you can choose to either open your own practice, buy an already established practice, or be hired by an older doctor after graduation. opening one's own dental practice has a very high success rate given that you choose a good location and, well, that you are a good dentist and interact well with patients. getting a practice loan is very easy for new doctors (according to older doctors and admissions people i have talked to.) if you would rather buy a practice or associate (work as an employee of the senior doctor) for a while after graduation, you can check newspaper ads, ads in dental journals, things like that for practices that are for sale or want new associates. you could also advertise yourself and see if any doctors contact you with an interest in hiring a new associate. once you find these practices, you would go to the practice and observe/interview with the other doctor and hopefully find a practice that you will fit in with.
in my opinion, once you have a doctorate or graduate degree of any type it is generally much, much easier to find a well paid and satisfying job in your field of interest.
Hope this helps.