How to find Private/RSA Keys

[Israel213]

First, I'm only playing on my machines against my accounts.(This is legal)

Haven't tried any packet sniffing in quite a while. Was trying on old site that I used to be able to view plain text via Wireshark and realized they had switched to TLS. After searching some sites and the wiki for Wireshark I saw that I need to find the location of the private rsa key and link it in Wireshark like here(Using Wireshark to Decrypt SSL/TLS Packet Data:: RouterZone). Only problem is I don't know where to find them and when I search for "*key*" from the command line I come up thousands of wrong entries. Anyone know how to find them?