Windows API in C/C++

Help, I have no idea how to correctly use the API to create windows and fill them with text and shit.

Give me information, tutorials, etc.


public class NotNull implements Rule {
  String objName = null;
  Object o = null;
 
  public NotNull(String objName, Object o) {
    this.objName = objName;
    this.o = o;
  }
 
  public void check() throws RuleException {
    if (o == null) {
      throw new RuleException(ErrorMessages.ErrorCode.OBJ_IS_NULL, objName);
    }
  }
}