This topic describes how to find the contenttypeID. You will need to enable the management of content types so that the you can review the list of content types associated with the list, open the content type, and copy the ID from the URL.
You will need to enable the management of content types for the list in order to access the List content types.
To Enable the management of content types
Navigate to the List Settings page and open the content type. SharePoint will reference the ContentTypeId in the URL.
To find the listID
Copy the URL and find the following the strong following ctype. The string may look like this:
"ctype=0x01006ACB74139E82C34FB9A168AE0D163CB4"
You can also retrieve the contentType ID using C#. For more information and a code sample, see SPContentType.Id.
Prerequisites for working with the API