You need to Google the POP3 settings for your e-mail provider and (most probably) the SMTP settings for your network (e.g. for T-Mobile in the UK it's smtp.t-email.co.uk). Don't forget to note port numbers.
Once you have the settings information, go into your e-mail app of choice and in the menu / settings you should find an option for adding an account. Tap this then follow the prompts, filling in the details you found above.
