Hello , I ask if any one can help me , by suggest tutorial .

I need make java app GUI which take String from user , and write this String in web page text field .

for example : username and password , when both are written on the GUI both are written in the webpage .

click on GUI affect Click on webpage , how can I make this .

tutorials , where I read ?

I'm not sure of your question.
By web page I assume you mean what is displayed in the window of a browser.
What is "Click on webpage" mean? Are you trying to position the cursor over the browser's window and click on the spot on where a Submit button is shown?

The Robot class can move the cursor, press the mouse button and type characters. I have no idea how your program would get the location of the input field and the Submit button on the browser's window.