Purchase unique stationery and a beautiful pen. Write the letter on the first page of stationary and put the entire package (paper, pen, and secret admirer note) on her desk or somewhere else he'll discover it. You can mail it to him if you know his address. To maintain your identity, leave out the return address. Alternatively, you could drop it under her door in person. The letter should be written such that it appears to be from someone who works with her and would have no reason to write to her personally. For example, you could write about current events or issues related to your work or school and sign it using your business name or logo. Include a gift item for her to show that you've taken the time to think of her and your relationship. This could be anything from candy bars to coffee mugs featuring pictures of her favorite movies or television shows. It's best not to use names in your note, but instead use symbols or abbreviations. This way, you remain anonymous but she knows who it is from. Also, don't use full sentences but instead use short phrases or single words. This way, he won't feel like you're sending him a text message but instead will feel like you're writing a personal letter. Finally, follow up! Let her know that you enjoyed their friendship and you hope she feels the same about you.