Feels like I'm just missing some key information to something many people think of as easy. So this is more a request to point me in the right direction rather than asking a specific technical question.
I have a Kenwood radio with a built in modem (terminal node controller or TNC) which accepts an 8N1 serial input. I want to have my Arduino (I have both an Uno and a Mega) connect serially and transmit data. I know where the serial pins are on the Arduino, I have some libraries (APRS.h and ax25.h, along with the .cpp files) and feel comfortable massaging square pegs into round holes. But while I have 25+ years of tinkering with stuff like this, I have a hard time coding from scratch.
Any homework assignment you'd care to point me toward would be appreciated. I am a teacher and it would be nice to tinker with this stuff in the classroom in a couple months.