Integrate Zoho rest API's

Question

I am trying to integrate Zoho rest API's to achieve below list of tasks.

Task List:

a) To get Project List b) To get Projects's Users list c) To get List of Task for the projects d) To Create new task

I have successfully generated access token by following this.

AccessToken and refresh token:

{
    "access_token": "1000.53ea059005781cfc.ff08c750c671f7d1267e6de1e",
    "refresh_token": "1000.2a5ddc41fb6faccb42.b6c01194764f259049187f",
    "api_domain": "https://www.zohoapis.com",
    "token_type": "Bearer",
    "expires_in": 3600
}

When i try get all portals operation, it gives me error like "Invalid OAuth access token." in the Postman.

In Documentation not much more details like what is request, what is URL etc given.

How can I send a correct request to Project List or Projects's Users list?

Any help would be highly appreciated.