You may do some awesome things with your site logo in the ShortPoint Theme Builder (e.g. make the logo redirect the users to a specific page). 

Nevertheless, changing the logo itself is a feature available through SharePoint Site Settings. Here are the steps:

STEP 1. Open the Site Settings.

Please click the cog wheel on the top of your site and choose Site Settings from the drop-down list:


STEP 2. Choose Title, Description and Logo.

Then, in the Site Settings menu, under Look and Feel, choose Title, Description and Logo:


STEP 3. Upload a Logo.


From here, you will be able to upload a logo from your computer or from SharePoint, as shown in the screenshot below:


 Press OK to save your changes.


Related articles:

How to Link Your Logo to a Page