IPhone won't let me send pictures?

I bought a 16gb unlocked iPhone off eBay and the phone company I'm with is cellularone. The phone won't let me send pictures even tho I have the data plan, it's like the picture button in the bottom corner of a message is off. I went to the settings and went to messages and there's no text their at all

Well first, I've never heard of that cell phone company and second go to creating a message and try form there

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