Xbee data send

ok, I will use long int if I can do this of course.
I using Serial transmit and receive.
What is the best way to collect data?
I was start to do something but I don't know is it right way.

void loop() {
while(Serial.available() >0) { //only when serial active
header = Serial.read(); // header gets 1st byte
if(header == 65) { // if header is 65 (A), bytes 1 and 2 are next two serial reads
byte1 = Serial.read();
byte2 = Serial.read();
}
}

Serial.print (byte1); // to see what I was received
Serial.print (byte2); // to see what I was received
}

with this I can see next 2 bytes after header A but I don't know how to stick together 6digits in one number (in one variable)
May be you can suggest some better solution and code.