OAuth for Google Calendar

Important note
If you do not have experience with Google oAuth authentication via a web app please do not offer your services. This will be a very simple job (mostly copy and paste) for someone with this experience; but may prove beyond the capability of someone without that experience!

Project description
I have a small web application written in VB.Net which we use for family matters.

I need an application to be able to access two existing Google calendars and add/update/delete events on those calendars. It will only ever be me accessing the calendars.

I have tried to authenticate using OAuth but am not getting anywhere! So I need some well commented code that will work for this: written in VB.net or Csharp (preferably VB.net).

Test of success will be a simple form (that I will provide) including the following buttons:

'Authorise':
Clicking this button will initiate the oAuth process with Google Calendar, and on success return the user (me) to the same page.

'Create event'
Clicking this button will create an all-day event with event id, start and end date, title, and description.

'Update event'
The same functionality as 'Create event' from a passed event id.

'Delete event'
Deletes the event of a passed event id

Resources
I will provide you access to my server so that any configuration issues can be dealt with. Also access to a sample Google Calendar, and a Client Id, and Client Secret to use.

The application name will be 'Farbrook manager'.

Your solution will be in the form of a dll and will allow me, at a later stage, to hard code:
- target calendar id
- client id
- client secret
- redirect URI

Any questions just ask.