Google Docs is a web based service from Google that provides word processor, spreadsheet, presentation, form, and data storage. Documents can be saved to computer in a variety of formats such as ODF, HTML, PDF, RTF, Text, and Microsoft Office format. With Google Docs, users can create docs within the web-based apps, import through the web interface, or send files via email. It also allows users to share, open, and edit documents online by multiple users at the same time.

How To Collaborate With Multiple Users Online Using Google Docs

• Log into Google Docs account to access documents & then click “Documents” in the top navigation bar.
• Click “Create New” and choose the types of documents you want to create.
• Once finish, the blank document with appear in screen. Name the document and click “Share” to invite others to view and/or edit the document.
• Add people by enter the email addresses to invite, and then click to denote “Can edit” or “Can view” options to begin collaborating with Google Docs. Note: Each document can only adds maximum 200 collaborators or viewers.
  
• When collaborators opens the document at the same time, owner can watch and chat with them by click the blue bar at the top right of the screen.
• After complete create the document, users can click “File” to download or print the document in a variety formats. Or click “Upload” to share the files to email.
  

Note: Users can access and view documents without a Google account via an invitation.

I believe this simple guide will able to help you to use Google Docs to collaborate with friends and colleagues online.