Is there any command? I want to create a fresh keystore file..
Depends. Which keystore are you referring here?
What is the purpose of the certificate you are trying to import?
I want to create keystore file using pair of certificate and key.
Do you have any command to do this in Siteminder?
So I am making an assumption here that you are referring to java keystore here (jks)
There is no CA tool to manage java keystore.
You need to use keytool which is shipped with jdk.
e.g
https://docs.oracle.com/javase/7/docs/technotes/tools/solaris/keytool.html
keytool -importcert -file certificate.cer -keystore keystore.jks -alias "Alias"