Hello Christina,
Welcome to Apple Support Communities.
To answer your question about syncing music to the iPod shuffle from multiple computers, just manually manage the music on the iPod as described in the article below.
iPod: Frequently Asked Questions
Question: I have a computer at home and one at work. Can I update my iPod music collection from more than one computer?
Answer: Yes. When you first connect iPod to your computer, iPod recognizes that computer as its "home" computer. Each time you connect, iPod automatically downloads the music library stored on it. When you connect iPod to a different computer, iTunes will inform you that iPod is linked to a different iTunes library and will ask whether you wish to erase iPod's contents and sync with the new computer's library. If you will be connecting to multiple computers frequently, configure your iPod to manually manage music. This will allow you to selectively drag songs, albums, or playlists from the second computer to your iPod without compromising the existing music.
Synchronization generally occurs only in one direction, from your computer to your iPod. This means you typically cannot transfer music, automatically or manually, from your iPod to a computer, and you cannot use iPod to copy a music library from one computer to another. An exception to this is the transfer purchases feature which allows you to restore purchased iTunes content to your computer from your iPod. Additionally, if you legally are allowed to copy music or other media files, you can configure your iPod as a storage drive to move media files.
Also, you can find more information about syncing and manually managing music in the iPod shuffle User Guide.
manuals.info.apple.com/MANUALS/1000/MA1550/en_US/iPod_shuffle_4thgen_User_Guide .pdf
Ciao,
-Jason