To post a group note:
1. Tap the Home tab > Groups > the group of your choice.
2. Tap Notes.
3. Tap "+" at the bottom right of the screen > Write.
4. Tap What's new? and write your note, then tap Post.
If you want to post a photo, you can do so using the Albums feature, which is specifically for posting and viewing photos.
Let us know if we can make it better.