Zoom's getting started videos: https://zoom.us/resources
The US phone numbers for Zoom are:
+1 312 626 6799 US (Chicago) +1 646 558 8656 US (New York) +1 346 248 7799 US (Houston) +1 669 900 6833 US (San Jose) +1 253 215 8782 US +1 301 715 8592 US
You can choose any number and use it for all meetings. When joining a meeting you will be asked for a meeting ID or access code. This will be the number in the meeting link. For example, if the link is https://zoom.us/j/123456789, the access code will be 123 456 789.