Chris,
You can go the the FCC link above and search 'Ship Radio Station Authorization', or try this link:
http://wireless.fcc.gov/marine/fctsht14.html
You will have to get a FRN registration number and then fill out the form FCC 605. After that you have to pay the fee and if you have filled out the form successfully, the FCC will issue a license online and mail you a copy. You will also need a Restricted Radiotelephone Operators License. No test, just pay more money!
There is a phone contact number and I would print out the application, fill it out and then call and ask to verify the correctness of the form prior to submitting it. You can submit the form and pay the fees online.
After checking on all this, some folks have decided to just go without the licenses and get the MMSI number from Boat US.
There was a long discussion here a couple of years ago about whether or not to get a license. I cannot advise anyone to forgo the license, that would be a personal choice. In Canada, boats use their boat name on the VHF, and you are going inland, probably well away from the coastal VHF and Canadian Coast Guard coverage.
To be legal with the US FCC you need both licenses.
Larry H