Facebook lets you upload and share photos with your Facebook networks and organize the photos into albums. If you want to replace one of your photos with a different one -- or a different version of the same one -- you can do so by uploading the new one next to the old one, then deleting the old one. This preserves the photo's position in the sequence within the album -- but any captions, comments or "Likes" attributed to the old photo will permanently disappear.
Log in to Facebook, click the "Account" link in the top right area of your homepage and click "Photos" in the navigation menu on the left side of the screen. This displays your most recently used photo albums and photos of you.
Click the "Photos" link next to "See All" in the "Your Photos" section near the top of the page. This displays all of your photo albums.
Click the album that contains the photo you want to replace. This displays all of the photos in that album, along with an option to add photos to the album.
Click the "Add Photos" button in the top right corner of the displayed contents of the photo album. This opens a photo upload panel.
Click the "Select Photos" button in the photo upload panel and open the photo you want use to replace the old photo. Facebook uploads the photo to the album.
Click the "Standard" or "High Resolution" radio button in the photo upload panel, and then click the "Done" button when the message "Upload Complete" appears. The panel closes and an "Edit Album" page appears.
Click the "Skip" button below the "Unpublished Photos" notification near the top of the Edit Album page. This closes the notification.
Click the "Back to Album" button in the top right corner of the Edit Album page. This displays the contents of your album again, including both the new photo and the old one.
Drag the replacement photo next to the one to be replaced. This ensures the new photo will appear in the same position as the old one in the album photo order.
Click the old photo, scroll down to the bottom of the photo viewing screen and click the "Delete This Photo" link on the left side of the screen. This returns you to the album contents page and completes the replacement.