how to pop a dialog box on button click

shalu

Hello Friends
I want to upload a image but according to requirement when click on button a pop window display and inner part of pop window display browse field using code something like

<form action="index.php" method="post" onsubmit="">
    <div><label>Name:</label> <input type="text" name="form[name]" /></div>
    <div><label>File:</label> <input type="file" name="form[file]" /></div>
    <div><input type="submit" value="SUBMIT" /></div>
</form>

actually i want to show this browse field in pop-up window.
Please reply me regard this
Thanks