If you haven't already configured mIRC to use SSL, please take a look at our Using SSL guide.
For the purpose of this document, we'll assume you already have the necessary OpenSSL DLL files and have setup mIRC to use them. To add your certificate, follow the steps below:
Now, when you connect to DareNET, prepend a plus sign to the port number to let mIRC know you'd like to connect using SSL:
/server irc.darenet.org +6697
Once connected, read how to add your certificate's fingerprint to N.