When you receive an invite to a video conference then it will incorporate all the instructions. Search for a join link in the invite and click on that.
When joining the very first time, it will ask to accept and install an extension for browser. The steps to accept and install an extension is similar for Google Chrome, Firefox, Safari and Internet Explorer. At this time Microsoft Edge is not supported, you should any other browser.
Installation steps when joining the first time.
You are in the video conference!