To change your appearance, you first need to create new body parts and wear them:

1. Click the inventory button at the bottom right of the viewer.  This will open an inventory window.
2. In the inventory window, right click on Body Parts.  Select New Body Parts -> New Shape.
3. You can give your new body shape a name if you like.
4. Do the same thing to create New Hair, Skin and Eyes.
5. These new body parts should all now appear in your inventory under Body Parts.
6. Select all the new body parts in your inventory (ctrl-click to select multiple) and right click to select Wear.
7. Now right click on your avatar and select Appearance...
8. The appearance window should now be displayed.  Down the left hand side of this window are a number of tabs that you can select and these will give you options to change particular parts of your appearance.  NOTE: At this point you will not be able to change your clothing
9. From the shape tab you have the option to make your avatar male or female.
10. Once you have customised your appearance, click Save All  and close.
11. You can now go back and change your appearance at any time by following steps 7 - 10

To change your clothing, you first need to create new clothing items and wear them:

1. Click the inventory button at the bottom right of the viewer.  This will open an inventory window.
2. In the inventory window, right click on Clothing.  Select New Clothes -> New Shirt.
3. You can give your new shirt a name if you like.
4. Do the same thing to create New Pants, Shoes, Socks etc.
5. These new clothes should all now appear in your inventory under Clothing.
6. Select all the new clothes in your inventory (ctrl-click to select multiple) and right click to select Wear.
7. Now right click on your avatar and select Appearance...
8. The appearance window should now be displayed.  Down the left hand side of this window are a number of tabs that you can select and these will give you options to change particular parts of your appearance.
9. Once you have customised your appearance, click Save All  and close.
10. You can now go back and change your appearance at any time by following steps 7 - 9.

IMPORTANT: Periodically, the OpenSim servers are restarted and when you log in the next time you may find that your avatar has gone back to the default "Ruth" avatar.  In this case, you need to wear your body parts and clothing again (step 6).