When i try to send

Hi, What you will need to do is get the correct settings on your phone, as this is why your getting that message.
There are two ways to do this the easiest is to contact your service provider and ask them to send you the Internet and MMS settings.They send you this via a text mesage that will automatically update your phone to the correct phone settings.
The other way you could try is going to your service providers website and most providers let you send the settings yourself to update your phone to the correct settings.
Both ways are easy so you won't have to change the settings yourself it is all automatic.
Let me know if you need any more assistance.