This is simple.
What you need is a HTML code.
<form name="form1" method="post" action="" enctype="multipart/form-data">
<input type="file" name="imagefile">
<br>
<input type="submit" name="Submit" value="Submit">
This will have the browse for file button and ask the user to select the files. For them to upload successfully, you will need to have certain validation in place.
