How to let others edit and save my word document on Facebook?

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Okay so I'm supposed to host a picnic and I made an event for it on Facebook. I need to find a way to let the guests sign up to bring food. In the past the hosts have made the sign up on a word document that people could edit and save so everybody knew what they were bringing but I've come across several problems. I cant add a word document to an event. The only way I could figure out to share a word document is through a group message but then the word document comes up as a read only and I tried to change around some word settings and finally came up with a version that can be edited, however I cant figure out how to make it save with the changes so everyone else can see it. If you know how to fix these problems or have any other ideas how to let people sign up please help me. I'm not good with computers so you need to walk me through it step by step.

[Smarty Smarticles]

What about Using Google Docs instead of Microsoft Word?
Google Docs is an Online document typing thinggy that is very similar to Microsoft Word but the only difference is, is that it's online and anything that's typed is automatically saved.

1. Make a Google Docs account.
2. Make a Document for your Picnic
3. Then tell everyone on Facebook to go to GoogleDocs.com
4. Tell them to type in the Password and username of the Google Docs account where you made the Picnic Document and they can edit the Document you made.

[Scanning]

Make a docx and make it public