If you're writing a letter to potential authors/artists/podfic artists, you can link it here or at the equivalent post on DW. You can also put your whole letter in a comment if you don't have a journal or similar to host it on. Wherever you put it, please include the link in your sign-up on AO3.
If writing a letter, please make sure it's complete and unlocked by 11 April.
If you're wondering what to put in your letter, try browsing through the 'dear creator' or 'dear writer' tags on DW/LJ, and use the letters you like as a model for your own. I suggest you include the following information at a minimum:
-your AO3 name
-the songs you're requesting
-the medium or media you're requesting for each song
-the prompts and DNWs you entered into your sign-up.
You may wish to use your letter to expand on your sign-up prompts, or just include lists of tropes you like or dislike.
Here's a possible template for linking your letter here. Use it if you find it convenient: