On my iPhone I am receiving text messages from a friend on an android device but they don't receive mine.
Messaging between iPhone devices work fine
@Way-El -- on your iPhone, you can send SMS using the device's cellular connection, to any device capable of receiving SMS over the recipient celluar connection.
Also, on your iPhone, you can use Apple's "iMessage" protocol over either WiFi or your "data" connection (if your account has "data") to send to another Apple device (iPad, iPhone).
Does your friend's Android device support the iMessage protocol ???
Can you configure your iPhone to use SMS to send?