Where to find ArcGIS service url and how to create one? How upload and view content from the server

[GeorgyFelix]

I am new to ArcGIS. I would like to know where I could find the service URL to list all the items in the MyContents tab which could be found by logging into my organization's ArcGIS URL. I want to do this using the Javascript or Rest API provided by ArcGIS.

I was able to get Token from ArcGIS using

https://www.arcgis.com/sharing/rest/oauth2/token

this URL.

When I try to upload a file to one of the sample servers using Code, I am not able to do it. It works in postman though.

These are the code that I used for uploading a file to a sample server which failed.

$.ajax({
 async: true,
 crossDomain: true,
 url: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/DamageAssessment/FeatureServer/uploads/upload",
 method: "POST",
 headers: {
 "Content-Type": "multipart/form-data",
 "Accept": "application/json"
 },
 contentType: false,
 processData: false,
 mimeType: "multipart/form-data",
 data: {
 "f": "json",
 "file": "C:/Users/georgy.f/Downloads/Screenshot_20190422-114420.jpg",
 "description": "descrioption",
 }
}).done(function(response) {
 console.log(response);
});‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Another code for uploading that I tried.

var uploadsettings = {
 "async": false,
 "crossDomain": true,
 "url": "https://sampleserver6.arcgisonline.com/arcgis/rest/services/DamageAssessment/FeatureServer/uploads/upload",
 "method": "POST",
 "headers": {
 "Content-Type": "multipart/form-data",
 "Accept": "application/json"
 },
 contentType: false,
 processData: false,
 "mimeType": "multipart/form-data",
 "data": form {
 "f": "json",
 "file": "https://images.pexels.com/photos/67636/rose-blue-flower-rose-blooms-67636.jpeg",
 "description": "descrioption",
 }
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

My aim is to list all the MapViews and SceneViews available in my organization.

Also, will I be able to view BIM models in ArcGIS using Javascript or REST API by somehow uploading it to ArcGIS server?