ถามวิธี query เช็ค id กับ pass หลังจากกดปุ่ม login บน popup ครับ

<div id="login-box" class="login-popup">
        <a href="#" class="close"><img src="images/close_pop.png" class="btn_close" title="Close Window" alt="Close" /></a>
          <form method="post" class="signin" action="#">
                <fieldset class="textbox">
            	<label class="username">
                <span>Username or email</span>
                <input id="username" name="username" value="" type="text" autocomplete="on" placeholder="Username">
                </label>
                
                <label class="password">
                <span>Password</span>
                <input id="password" name="password" value="" type="password" placeholder="Password">
                </label>
                
                <button class="submit button" type="button">Sign in</button>
                
                <p>
                <a class="forgot" href="#">Forgot your password?</a>
                </p>
                
                </fieldset>
          </form>
		</div>