How do I change the roundcube logo to my own?

How do I change the roundcube logo to my own? Ubuntu 15.10
What are the paths? Where do I put my logo? What are the exact steps to change to my logo on the login and the interface? What size should my logo be in pixels?
I followed: https://www.howtoforge.com/tutorial...pureftpd-bind-postfix-doveot-and-ispconfig/3/
I looked at this tutorial but the paths are not the same: https://topicdesk.com/faqs/roundcube-installer/roundcube-change-logo/

 

Ok,seems like it will work except where is the "images" folder I uploaded it to /etc/roundcube/header_logo.png . It looked like it tried to change it but the picture is broken.
"edit"
I uploaded it to: /usr/share/roundcube/skins/larry/images/ I changed the picture to roundcube_logo.png

I made changes to: /etc/roundcube/config.inc.php

 

To change the roundcube webmail login page attributes via custom config file..
Actually roundcube is very flexible to change many things. All the attributes are in the main config file to play over. Here the idea we provide is not to go and change anything on the original config file, but we adding our custom webmail config file together with the original. So,in future if there is any updates, we simply just include this custom file again - That's it..!
Tricks to change Roundcube webmail title, logo image, f
ref: vvcares blog
Create a new file called 'custom_config.inc.php'
Include these attributes inside the php file
$rcmail_config['username_domain'] = '%n';
preg_match("/[^\.\/]+\.[^\.\/]+$/", $_SERVER['HTTP_HOST'], $matches);
$rcmail_config['product_name'] = $matches[0];
$rcmail_config['skin_logo'] = '../logo.png';

Place this file into the same location of the original config file (Eg: /etc/roundcube/custom_config.inc.php)
Include this file entry at after the very last line of the roundcube webmail's config.inc.php
Eg:
// end of config file
include 'custom_config.inc.php';