The easiest way is to use the WebSphere console.   The websphere must be running.    You can attach to the console via a web browser using the URL in this form:

http://your-host-name:NNNN/ibm/console

where:

your-host-name will be replaced with the actual host name
NNNN is the value of the "Administrative console port" found in the file "AboutThisProfile.txt" located in the the WAS profile under the "logs" directory

Once you are in this console, down the left side are navigation, go under Security / SSL Certificate and Key Management.   From there "Keystores and Certiicates".  On this page should be 2 keystores, there should also be help link on the far right labeled "About this page". 

From here it branches into all sorts of possibilities and you should find more info in the WebSphere documentation.