How would I send a line to the Arduino that is multiple characters long?
Type it into the Serial Monitor and click on Send (or hit Enter). Type it into a terminal program that is connected to the COM port that the Arduino is on. Send it to the COM port from a program. In all the above cases, send more than one character.
mattmac553: How would I send a line to the Arduino that is multiple characters long?
Is your real question how to receive and interpret a multiple character input to the Arduino rather than how to send one ?
If so, see http://gammon.com.au/serial