If you want to send files via email from your own email account then you can set up an out going email server.
Open the App Settings and open the "Email" section. View
Tap on "Outgoing Mail Server". Then tap on the "+" button to add an account and enter your email provider details.
Use the "+" button in the top of the edit settings screen to choose an account type or enter your own server details.
Your email server will probably require your username and password. Tap on the "Requires Username" setting to enter these details.