Here's a web site for a start:
http://www.eham.net/
It's not simply a matter of applying for a license. You need to pass a test or two (including Morse Code). Various bookstores sell the kit for learning Morse and the radio requirements for the test. I believe that you would need a General Class or higher to take advantage of HAM, so that's more than one test.
Another option is SSB radio email. Do a Google search on "SSB Email" for options. An SSB radio license is simple, you need to go to the FCC page, and can apply on line. This is NOT the same as a HAM license.
the third option is simply to have email only when in port, which is a lot cheaper and simpler - you can find internet cafes everywhere.
Fair winds,
Jeanne