With regards to setting up a POP3 email account, please open the Inbox application; click on Services > Options > Add > Choose IMAP4 Mail or POP3 (depending on your mail service) and click OK on the in the top right-hand corner.
On the next window ‘POP3 Mail Service Definition’; choose ‘Network Connection’ for Connection. The POP3 Host details can be found from your mail service provider. The User ID and Password is your personal details for that specific email account.