Unable to send post request

var

Client: HttpClient;

Headers: HttpHeaders;

Content: HttpContent;

Url: Text;

MyContent: Text;

TempBlob: Record TempBlob;

APIResult: Boolean;APIOutput: Text;

AuthText: Text;

begin

Client.DefaultRequestHeaders.Add('Accept', 'application/json');

Content.Clear();

Content.WriteFrom(MyContent);

Headers.Clear();

AuthText := StrSubstNo('username:password');

TempBlob.WriteAsText(AuthText, TextEncoding::Windows);

Headers.Add('Authorization', StrSubstNo('Basic %1', TempBlob.ToBase64String()));

Headers.Add('Content-Type', 'application/json');

Content.GetHeaders(Headers);

if not Client.Post(Url, Content, ResponseMessage) then begin

Error('The call to the web service failed.');

end;

Headers := ResponseMessage.Headers();

ResponseMessage.Content().ReadAs(APIOutput);

Message(APIOutput);

EXIT(ResponseMessage.IsSuccessStatusCode());

At the Headers.Add('Content-Type', 'application/json'); get the following error:

Element 'Headers' is not a member of 'Content'

Think this is caused by the previous line, been unable to find anywhere online where this error has occurred previously. Been struggling with this for days, have tried without the authorization but still the error the same.