You needed to figure out how to post photos on iPhones...
To post photos there are 2 methods. One where you use the photo library and one where you take the photo on the spot.
1- Tap 'Photos' icon (the icon to the right of the camera button and above the keyboard).
2- Select the correct album.
3- Select the correct photo
4- Tap 'upload'
5- pick the desired size of the photo
Or:
1- Click the camera icon
2- Take a photo
4- Click use photo
4- Click upload
5- Tap the desired size