To view an existing account, first log into the Admin API on the administration server using a profile that has the Administrator role. For example:

POST /ccadmin/v1/mfalogin HTTP/1.1
Content-Type: application/x-www-form-urlencoded

grant_type=password&username=admin1@example.com&password=A3ddj3w2&totp_code=365214

Then issue a request to the getOrganization endpoint, providing the ID of the account you want to view, and including the access token that was returned by /ccadmin/v1/mfalogin. For example:

GET /ccadmin/v1/organizations/100002 HTTP/1.1
Authorization: Bearer <access_token>

The response shows the predefined account properties that are exposed by Commerce Cloud, and the values of the properties in the specified account. Note that the members property is an array in which the elements are the IDs of the contacts for the account:

{
    "customerType": "Supplier",
    "contract": {
        "creationDate": "2016-10-17T20:25:44.000Z",
        "startDate": null,
        "externalContractReference": "",
        "description": null,
        "catalog": {
            "repositoryId": "cloudCatalog"
        },
        "terms": null,
        "priceListGroup": {
            "repositoryId": "defaultPriceGroup"
        },
        "endDate": null,
        "displayName": "Sherman",
        "repositoryId": "100002"
    },
    "vatReferenceNumber": null,
    "links": [
        {
            "rel": "self",
            "href":
"http://myserver.example.com:7002/ccadmin/v1/organizations/100002"
        }
    ],
    "organizationLogoURL": null,
    "type": "company",
    "repositoryId": "100002",
    "dunsNumber": 000000000,
    "uniqueId": null,
    "id": "100002",
    "description": "Supplier of sprockets to a wide range of industries.",
    "name": "Sherman Sprockets",
    "active": true,
    "secondaryAddresses": [
        {
            "address": {
                "postalCode": "02116",
                "phoneNumber": "1-555-555-1212",
                "state": "MA",
                "address1": "1 Wixom Street",
                "address2": null,
                "companyName": "Sherman Sprockets",
                "repositoryId": "120002",
                "country": "US",
                "city": "Boston"
            },
            "addressType": "Sherman"
        }
    ],
    "billingAddress": null,
    "taxReferenceNumber": null,
    "shippingAddress": {
        "postalCode": "02116",
        "phoneNumber": "1-555-555-1212",
        "state": "MA",
        "address1": "1 Wixom Street",
        "address2": null,
        "companyName": "Sherman Sprockets",
        "repositoryId": "120002",
        "country": "US",
        "city": "Boston"
    },
    "members": [
        {
            "repositoryId": "110001"
        }
        {
            "repositoryId": "110002"
        }
    ],
    "organizationLogo": null
}

You can modify the values of the properties of an account using the PUT /ccadmin/v1/organizations/{id} endpoint on the administration server.