Why can't I send pictures to anyone that don't have an iPhone??

do you have a data plan with your carrier?

This is an issue with MMS (Multimedia Messaging System) which is controlled by your carrier and requires an activate Cellular Data (Mobile Data) connection.

Source: http://support.apple.com/kb/ts2755

If you can't send and receive MMS

You will need these to send and receive MMS:

• An iPhone 3G or later
• iOS 3.1 or later
• A cellular data connection (MMS isn't available if you're using only Wi-Fi)
• A domestic MMS plan from your cellular provider. You might need an international messaging plan to send MMS to an international contact (Contact your carrier for more information.)
• A roaming MMS when using a cellular provider's network that is different from your billing cellular provider's network (Learn more about roaming and contact your carrier for more information.)

To resolve issues with sending and receiving MMS, follow these steps

1. Go to Settings and turn airplane mode off.
2. Go to Settings > Messages and turn MMS Messaging on.
3. Go to Settings > Cellular and turn Cellular Data on.
4. Go to Settings > Cellular and turn Data Roaming on if you're roaming on a cellular provider network that is different from your billing provider's network.
5. Make sure that you have a cellular data connection in the status bar of your iPhone.
6. Go to Settings and turn Wi-Fi off. Open Safari and navigate to www.apple.com to verify that you have a data connection. Turn Wi-Fi back on to continue using Wi-Fi for other features. If your cellular data connection isn't available, follow these steps.
7. Make sure that you can send and receive SMS. If you can't send and receive SMS, see the "Issues with sending and receiving SMS" section, above. MMS might not be available while you're on a call. Only 3G and faster GSM networks support simultaneous data and voice calls. Learn more about which network your phone supports.
8. Restart your iPhone.
9. Tap Settings > General > Reset > Reset Network Settings on your iPhone.
10. Remove your SIM card and insert it again.

If you still can't send or receive MMS, follow these steps

1. Make sure that the contact trying to message you isn't blocked in Settings > Messages > Blocked.
2. Go to Settings > Messages and turn on group messaging if you're sending a group message.
3. Make sure that you're using the area code with the contact's phone number. When you send messages internationally, you also need the contact's international code.
4. If you're using a "Pay as you go" MMS plan, make sure it has enough available balance. If you're unsure of your MMS plan or available balance, contact your carrier.
5. If the issue occurs with a specific contact or contacts, back up or forward important messages and delete your current messaging threads with the contact. Create a new message to the contact and try again.
6. If the issue occurs with a specific contact or contacts, delete and recreate the contact from the Contacts app. Send a new message to the new contact.
7. Back up and restore your iPhone as new.
8. If your carrier has recently ported your phone number, the porting process might not be complete. Contact your carrier to confirm that the porting process is complete.
9. Contact your carrier to verify that you're provisioned to send SMS and are in an area with cellular coverage.
10. Contact your carrier to verify that there aren't blocks or filters on your wireless account preventing you from sending SMS.
11. Your carrier might require modified APN settings to use MMS.

Further troubleshooting and information

• Follow these steps if you can't deactivate iMessage or if you can't send SMS to non-iOS devices because they are sent as iMessage.
• Get help if some of your SMS messages aren't displaying correctly.
• Follow these steps if you're receiving SPAM in Messages.
• Japan: Follow these steps if incoming MMS are received as group MMS.