2)Clink Open, then Browse:
3)Navigate to Truststore, then Open: (trustore.jks)
4)click OK
5) Enter pwd then click Ok
6)Select signer certificate from dropdown.
7) Lcisk Add then browse
8) Select Cert to add then click open.
9) Click Ok.
10) Enter a label then OK
11) done, new cert has been added.
Reference: https://www.ibm.com/support/knowledgecenter/en/SSKM8N_8.0.0/com.ibm.etools.mft.doc/ap34020_.htm