If you're looking to have your own button to upload a file instead of using <input type="file" />, you can do something like:

<input id="myInput" type="file" style="visibility:hidden" />
<input type="button" value="Show Dialog" onclick="$('#myInput').click();" />

Note that I used visibility: hidden, instead of display: none. You cannot call the click event on a non-displayed file input.