PHP checkbox set to check based on database value

Extract the information from the database for the checkbox fields. Next change the above example line to: (this code assumes that you've retrieved the information for the user into an associative array called dbvalue and the DB field names match those on the HTML form)

<input type="checkbox" name="tag_1" id="tag_1" value="yes" <?php echo ($dbvalue['tag_1']==1 ? 'checked' : '');?>>

If you're looking for the code to do everything for you, you've come to the wrong place.