Hello irshad,
You can set up local logging on the PIX memory buffer or direct the syslog messages to an external server. for local logging, u can use the command:
logging buffered
logging trap 5 (notifications)
logging on
You can see the messages by giving the command "show logging"
you can also direct these messages to a server, as told before. you can use the command:
logging host inside 10.1.1.1 tcp/1468 (default syslog port)
hope this helps.. all the best..
Raj