Writing data from my app to csv & upload it?

I wondered if it's possible to write some data to csv file in the documents path, or other convenient readable file. For example - i have a few text fields that i want the user to fill & then i want him to click "send" & after that the information will be written on a file that i could easily read & upload to my server. In my case i have an app that i want people to register for my members club, with first name, last name & phone number & i want to take this information & read it easily after is uploaded to my server. For testing i'm using my dropbox account as a server.

Is it possible?

Thanks for the help :)