Dear Suzanne,
This thread is not about serial communication, but this
http://e2e.ti.com/support/arm/sitara_arm/f/791/p/223353/1070752.aspx#1070752
is about it. It only differs that we are using BBBs UART lines, but if you use USB the only difference will be your peripheral will appear as /dev/ttyUSB0 instead of our /dev/ttyOx.
You have there also example codes.
An important thing is to have proper permission for the device node which can be set in ueventd.rc which is located in the root of your firmware.
Good luck with the porting and Happy Women's Day :)
best regards,
sodjas