ok, so which pins did you use?!
#include <SoftwareSerial.h>
//setup
SoftwareSerial mySerial(2, 3);
//loop
char c;
if (mySerial.available())
{
c = (char)mySerial.read();
if (c=='H')
{
///// if the key is a letter H do your code here
//comprende?
}
}