Hi, Ursula. :-) Assuming you're already signed in:
To reorder ALL images, from your portfolio/profile page --
Click 'Images' tab, then click 'Position' button under each image and choose a number.
To reorder within your individual galleries, from your portfolio/profile page --
Click 'Galleries' tab, then click the 'Edit' button beneath any gallery logo, then use the 'Position' buttons to choose order.
Hope this helps!