I did the exact same earlier myself, when I first posted a picture of Bob's family (part one). It was also upside down.
As for choosing an avatar:
1. Click on 'Settings' (top right) just before 'Log Out'
2. On the third column section @ left (My Settings) click on 'Edit Avatar'
3. Option 2 - click on 'Choose File'
4. Upload the picture of your choice from your picture's files in your computer by double clicking on it
5. Click on 'Save Changes' - bottom right