Hi I’am a begainner in this vb and I don’t know how to use API, I need some one to explaine the following code as an example and if there any books or websits that explaine API please tell me

Private Declare Function SendMessage Lib "User32" Alias "SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long

i have many codes using api, but i can not creat one, this is my problem ..