1. Connect to internet
2. Make sure your office document is put in Dropbox storage
3. Use CloudOn to open and edit this office document
In case of mail attachments, you can use 'open with' feature to open the doc using CloudOn. MS Office is installed in CloudOn's backend servers and use that to let users to edit the documents. The free version of the application is pulled from iTune Application store due to heavy demand and should be available soon.