Welcome to FT, Matrim33.
Yes, the agent can help you search for an award, OR you can find one online and phone in. Both methods are commonplace and will work. I find that it's far easier if you do your homework and actually have flights in mind and can call the agent with the fight numbers of the route that works best for you. That does not mean, however, that the agent will find award availability on flights that aren't showing award availability online. Sometimes the agent can see things or suggest routes that you didn't find, but it can also go the opposite way-- sometimes "phantom availability" shows up online, but it's actually not there to be booked. You see it, but neither you or the agent can actually book it. That issue shows up more in some programs than others.
As another aside, sometimes there will be a fee if you use and agent to book your award, such as on AA. The workaround there is to have the agent put the flights on hold, and then book them yourself online. AA offers a free 5 day hold, most other airlines do not.