Open your download folder and double-click the file named cacert.crt.
The Keychain Access application will open and you will be presented with the Add Certificates dialog box. Ensure that you select the X509 Anchors keychain from list of choices that are presented. Click OK to import the UConn root certificate into your keychain.
To add the certificate to the keychain you will be asked to authenticate with your computer's login/password (note: this is the same password you use when installing system updates).
Congratulations, you're done! Quit and relaunch your web browser in order to ensure your changes take effect.