This assumes you are already created an app in https://developers.facebook.com. If not, check out my article Getting Started with Facebook Graph API.

This also assumes you have a Page Access Token. If not, check out my article Get Access Token.

1. Go to https://developers.facebook.com and select My Apps.
2. Select your App.
3. Select Tools > Graph API Explorer.

By default, the query should be setup to GET v18.0/me?fields=id,name. Select Submit and this should return your User ID, something like this.

{
  "id": "1234567890123456",
  "name": "John Doe"
}

And User Access Token, something like this.

EAANROE66DrsBOy1TiJVQPEPEZAgo2Iap7QzdKEGRfJBW30drpIpkprZB4N5MRxDfZCoLh4OQZCCDgPqVxFEO39YDTIZCmChr9b3QcDr5MxPSjxvnY4Q1uPpMZCgG6Tr0FsZAW2vJD3qo5LpYZCu2JE2VhBUZCAPnZCCnysHlvca9QQ9BS2cvXxccHmUGPEKml4ncE0BYrfh7bI9ZAL9M7sLBgZDZD