PSTN Management

How can I configure asterisk to handle 4 PSTN lines. To connect asterisk with PSTN lines I have SPA400.

The Cisco SPA400 Internet Telephony Gateway with 4 FXO Ports is now obsolete (past End-of-Life and End-of-Support status). so you will need to figure out your self doing some google research or use a Digium card which provide an installation guide and comercial support from Digium