Literally all you need to do is...
1. Click the file in announcements to download it. You want the one with the 23rd February on by the way
[You must be logged in to view images. Log in or Register.] (I'd link it here but then you wouldn't learn to look there next time)
2. Open the zip file (that you just downloaded) and hit "extract". It'll then ask you where you want the files put.
3. You want to select your P99 folder and extract there, saying "yes to all" when it asks to overwrite.
:: Don't extract it to your screenshots subfolder, don't extract it to any other subfolder.
:: For me it's C:/P99/ , not C:/P99/Screenshots etc (can't find my backslash key)
...and that's it. Once extracted in the right place you'll be able to select your characters again.