Welcome to Android Central! What device do you have? What is it you're trying to do exactly? You want to send a photo via the Messaging app as a text message? I'm not sure what you mean about sending a wallpaper. What is the "group play" icon you're talking about? Do you mean Google Play?
Is your Messaging icon still somewhere on the homescreen? If not, open the App Drawer (the screen with every app you have installed), find the Messaging app, and drag and drop it to a homescreen. Now open the Messaging app, and select someone you want to send a message to. When you're composing a message, there should be an option to Attach File or Attach Photo (it might be a paperclip icon, or you may have to press the Menu button again to get it). If you select that option, you should see your photos come up--you can now select the photo in question, and send it.