how to change url of logo on DW Page?

The fast and easy way is to change the logo file directly from here: wp-content/themes/dw-page/assets/img/logo.png. The fix size for the logo is 60 x 170px. In case you want to have a bigger logo image, you will need to alter the CSS. Here is the way how to do it:

Step 1 Go to Dashboard > Themes > Editor then select the style.css file

Step 2 Add the following code into the end of the file style.css:

 .navbar .brand {
width: 200px !important;
height: 60px !important;
}

Also, you can refer to here: http://cmspioneer.com/designwall/blog/dw-page-faq/

Hope this helps !
Regards,
Dominic