The Stunnel configuration file (Stunnel.conf) is located in the C:\Program Files\stunnel\ directory. You will need to edit this file to secure your Trac site. Below is a good default config file. Simply replace the contents of Stunnel.conf with this, and edit the IP Address on line 17.

Sample stunnel configuration file by Redrock Software

; identify the private key and public certificate files
cert = cert.pem
key = key.pem

; Some performance tunings
socket = l:TCP_NODELAY=1
socket = r:TCP_NODELAY=1

; Some debugging stuff useful for troubleshooting
; debug = 7 for verbose logging 1 for emerg only
debug = 3
output = stunnel.log

; Service-level configuration
[https]
accept = 443
connect = 192.168.0.1:81
TIMEOUTclose = 0

For more details about stunnel, goto the Use SSL Encryption to Secure Your Trac System documentation.