I don't believe the Cisco ASA add-on has any sort of setup page. What exactly are you trying to do? Have you taken a look at the documentation for that add-on?
In order to ingest Cisco ASA logs you'll want to start by sending data via syslog from your Cisco devices. This section of the document covers it but may be a little vague if you've never configured Splunk to receive syslog before, or configured a syslog receiver such as syslog-ng.
I would consider reviewing the below documents if you've never done this before.
Essentially you'll either setup a syslog receiver such as syslog-ng to drop the syslog events into a file. Then Splunk can monitor the file and place it in the proper sourcetype defined here:
You can also configure Splunk to accept the input directly, but best practices suggest you use syslog-ng.
Let me know if you have any other questions.