If you click on a picture in your album, there should be a textbox towards the bottom of the page with the label 'Picture URL', and a value that begins with
http://www.fishlore.com/fishforum/members/...
Copy the contects of that textbox to the clipboard.
To make that picture your avatar: Go the edit avatar page. Towards the bottom of that page is another textbox, this time with the label 'Option 1 - Enter the URL to the Image on Another Website'. Paste the URL you copied into that box (make sure you notice the size limits on avatar images), and hit the Save Changes button.
This may require that the picture be in an album marked as a Public album.
To use that picture on your profile: Go to the profile customization page. Find the section where you want the image to appear (usually 'Main'), and paste the URL you copied into the 'Background Image' textbox in that section. Make sure to hit the Save Changes button at the bottom of the page.
This may require the picture to be an album marked as a Profile album.