When you upload files in your galleries, they are displayed in alphanumeric order by default, but you have multiple options for sorting them once they're uploaded.
Sort Files
To sort alphabetically, go to Sort by > Filename A-Z or Filename Z-A.
To sort files by timestamp, go to Sort by > Timestamp Old-New or Timestamp New-Old.
To randomize your files, go to Sort by > Random.
You can also filter your files by albums and by image favorited or hidden by the Linked Contact.
Rearrange Files
To sort files in a custom order, drag and drop the files into the order you'd like. If the file has an outline, that means it's selected.
(Pro-tip: to sort files in batches select the first file and hold down the Shift key while selecting the last file. All of the files in between will be selected.)
Use Albums
You can sort your files into albums, which are like folders or groups of files within a gallery. For example, if the Smith Wedding is your gallery, you might have albums for Ceremony, Reception, etc. For a sporting event, a photographer might set up albums for each team, game, and/or day of a tournament.
Learn more about using Albums and their benefits here: Using Albums