{
  "kind": "calendar#event",
  "start": {
    "dateTime": 04/10/2012 08:00 AM
  },
  "end": {
    "dateTime": 04/10/2012 08:00 AM
  },
  "attendees": [
    {
      "email": "myemailaddress@gmail.com",
      "displayName": "My Name",
      "organizer": True,
      "self": True
    }
  ],
  "reminders": {
    "useDefault": True
  }
}

'Code to create JSON using Dictionary Objects and Collection Objects
Dim d As New Scripting.Dictionary
Dim c As New Collection

d.Add "kind", "calendar#event"
d.Add "summary", "Event Title/Summary"

Dim d2(4) As New Scripting.Dictionary

d2(0).Add "dateTime", "2012-04-14T16:00:00.000-04:00"
d.Add "start", d2(0)

d2(1).Add "dateTime", "2012-04-14T18:00:00.000-04:00"
d.Add "end", d2(1)

'First Attendee
d2(2).Add "email", "john.doe@gmail.com"
d2(2).Add "displayName", "John Doe"
d2(2).Add "organizer", True
d2(2).Add "self", True
'Add attendee to collection
c.Add d2(2)

'Second attendee
d2(3).Add "email", "suzy.doe@gmail.com"
d2(3).Add "displayName", "Suzy Doe"
'Add attendee to collection
c.Add d2(3)

'Add collection to original/primary dictionary object
d.Add "attendees", c

'Add more nested pairs to original/primary dictionary object
d2(4).Add "useDefault", True
d.Add "reminders", d2(4)

'Now output the JSON/results
'This requires the VBJSON module (named just JSON, a module, not a class module)
Debug.Print JSON.JSONToString(d)

{"kind":"calendar#event","summary":"Event Title/Summary","start":{"dateTime":"2012-04-14T16:00:00.000-04:00"},"end":{"dateTime":"2012-04-14T18:00:00.000-04:00"},"attendees":[{"email":"john.doe@gmail.com","displayName":"John Doe","organizer":true,"self":true},{"email":"suzy.doe@gmail.com","displayName":"Suzy Doe"}],"reminders":{"useDefault":true}}

Dim objXMLHTTP As MSXML2.ServerXMLHTTP
Set objXMLHTTP = New MSXML2.ServerXMLHTTP
Dim sPostData As String
sPostData = JSON.JSONToString(d)

Dim sURL As String
sURL = "https://www.googleapis.com/calendar/v3/calendars/{mycalendarid}/events?sendNotifications=false&fields=etag%2ChtmlLink%2Cid&pp=1&access_token={my oauth2.0 access token}"

With objXMLHTTP
    .Open "POST", sURL, False
    .setRequestHeader "Content-Type", "application/json"
    .Send (sPostData)
End With

Debug.Print objXMLHTTP.ResponseText

Set objXMLHTTP = Nothing