My work profile is pretty similar:
1. click the + icon and choose state > net > wifi connected
2. set the ssid for my work's wifi. then press the top left tasker icon.
3. it'll kick you back to the home screen with a pop-up and choose 'new task +'. Give it a name (e.g."work")
4. Next screen is for you to set an action for when it's connected to wifi.
5. Press the + and audio category
6. Choose what you want set. One action at a time. Mine is has ringer, notification and media volume set to 0 and vibrate on.
And that should be it! Once you're done press the play icon.
I have a similar profile for when it's connected to my home wifi, but with the addition of turning everyone loud and turning off my pattern unlock. If you want to disable pattern/pin unlock, you need to get SecureSettings in the play store. It's a tasker plugin (
https://play.google.com/store/apps/details?id=com.intangibleobject.securesettings.plugin&hl=en) and will be located in the "plug-ins" category