How To Make SP-API Call in C/AL

Hey i am working On Business Central Integration With Amazon Seller Account. i am very beginner to C/Al and Business Central ( internee Level) . Can anyone Help me in that if anyone had done this integration before. i created LWA Access Token with HTTP Post method now next to make API call to Order, Inventory endpoint i need to first get AWS Signature but i dont have any idea about this type of authorization my LWA Access token Code is here.

codeunit 80100 “LWA Access Token”
{
trigger OnRun()
begin

end;

procedure Refresh_LWA_Token(): Text
var
    client: HttpClient;
    cont: HttpContent;
    header: HttpHeaders;
    response: HttpResponseMessage;
    //  Jobject: JsonObject;
    tmpString: Text;
    TypeHelper: Codeunit "Type Helper";


    Client_ID: Text;
    Client_Secret: Text;
    grant_type: Text;
    refresh_token: Text[10000];
    ResponseText: Text;


begin



    Client_ID := 'xxxxxxxxxxxxx';
    Client_Secret := 'xxxxxxxxxxxxxxx';
    grant_type := 'refresh_token';
    refresh_token := 'xxxxxxxxxxxxxxxxxxxxxxxx';


    tmpString := 'client_id=' + TypeHelper.UrlEncode(Client_ID) +
       '&client_secret=' + TypeHelper.UrlEncode(Client_Secret) +
       '&refresh_token=' + TypeHelper.UrlEncode(refresh_token) +
       '&grant_type=' + TypeHelper.UrlEncode(grant_type);


    // Jobject.WriteTo(tmpString);
    cont.WriteFrom(tmpString);
    cont.ReadAs(tmpString);

    cont.GetHeaders(header);
    header.Add('charset', 'UTF-8');
    header.Remove('Content-Type');
    header.Add('Content-Type', 'application/x-www-form-urlencoded');

    client.Post('https://api.amazon.com/auth/o2/token', cont, response);
    response.Content.ReadAs(ResponseText);
    if (response.IsSuccessStatusCode) then begin
        Message(ResponseText);
    end
    else
        Message(ResponseText);


end;

var
    myInt: Integer;

}