I am going to write this article in English, so my sister can read it.
First of all, u need to believe it is very easy, I just tried, here is step by step tutorial.
1. go to google console via your web browser.
https://console.developers.google.com/apis
you're gonna have to login to your google account first.
2. create a new project for this.
add a new project
click create
new project created
3. Enable "Google Calendar API" in the "Library" menu
click "Library" menu int the picture above.
search API "calendar" and press "Enter"
click "Google Calendar API" found.
click "Enable"
4. Create your app and set it up
click "CREATE CREDENTIALS"
choose "User Data" and click "Next"
name your app and choose your self as the app supporter
upload an icon for the app, type your EMail and save it
5. decide the information your users need to provide to you
so you can know who they are.
just click it.
choose what you want to know from your app users, for example, their email for further contact or event notify.
click "Update" after finish choosing
then save it
6. create your app's client id and put it in your web page javascript
So the Google API server will know that it is your app, not others'.
name your client id that you will put in your web page javascript
set the domain that you are going to use your app (the Google calendar API), so other hackers' domain will not be able to use it
click "Create" to create your app's client id
copy it and past it in your notepad for latter use, as you can see, for testing purpose, you need to add users for testing this app. by default, no one can use it ! I will explain how to do it latter.
client id created, you can copy it again any time you want.
7. create your API key for google server to check your quota and access
for this project, you may create multiple API keys, and put them in different web page. So google will log their behavior separately.
create API key
API key created, you may want to restrict it's use from web page only, so other hackers will not be able to try it from the windows app they wrote.
make some restriction rules.
8. add app testing users
as we mentioned before, you need to add testing users, or no one can use it.