Button that goes to another page and returns the passed value

Hello, I would like to know how I make a button to get data from another page ... type if on page 1 I inform the protocol and valid with a captcha and click on send, I would like to know how do I send this to pick only the protocol that I typed in the last page .... example I have this page with all the protocols I want to get only what I typed

This is the code that sends after completing the protocol and the captcha field aew has the button that sends Follow the code sees if it's right .....

public String insert() {
        try {
                if(ca.execute()){

                try {

                 this.getprotocoloString();


                } catch (Exception e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                }

                }
        } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
        }
        return protocolo;
}