Free servers support POP3 and IMAP only.
SMTP is not available with free account however you can use SMTP service from your ISP mail servers to relay mail by setting MX record in your 000webhost CPanel to point to your SMTP service provider.
To setup POP3 or IMAP, in your CPanel, under Manage Email Accounts will have instruction on how to setup POP3 or IMAP client like Outlook, Thunderbird, etc.
You can also use webmail in your CPanel to read email but you won't have a copy of your email.
In order to have a copy of your email, please use the POP3 email client to access your email, be sure to keep a copy of all your email on your PC. Restore email on free account is not possible.
To avoid these limitations, please upgrade to paid hosting at http://www.000webhost.com/upgrade