Arduino UNO Rev3 - Serial Comunication


I'm working with Arduino UNO ad Matlab, i have to send some information from a user interface to the Arduino and i do it using USB. The thing is that i have to tell it 2 diferent things: for example, i have to light a led and set the time that it'll be on, but that time is fixed by the user. I have no problem to send a char that set the led on, but i have no idea how can i do for sending 2 diferent comands and read it from the arduino.

Sorry my english.