How do I display my rectangle logo in the navbar instead of the square logo on the left side of the home button?

you can remove the logo, or other sections from the community using your CSS knowledge in Admin Panel> Theme> Advanced Setting> CSS code. 

Insert the following code to delete the logo:
 

.header-logo {
display: none !important;
}

You can add your logo to the navbar. 

To do this, you need to insert the line below to the Admin Panel> Theme> Navbar> Links:

<img src="https:URL OF THE PAGE YOU HAVE UPLOADED YOUR LOGO IN" style="height: 25px; margin-top: 2px; background: #ffffff;" /> | https://URL59 OF THE WEBPAGE YOU WANT YOUR NAVBAR TO DIRECT TO | start

Note: 

1. You first need to have your logo uploaded somewhere on the net. Then copy and paste the whole url for your logo and replace it with "URL OF THE PAGE YOU HAVE UPLOADED YOUR LOGO IN"

2. You can define any height, margin, and background color just be careful not to make it a huge size so that the interface will be out of control. 

3. Replace the https://URL59 OF THE WEBPAGE YOU WANT YOUR NAVBAR TO DIRECT TO with the URL of the page you want your logo to direct to. It mean, when your click on the logo in the navbar, it takes you to a certain webpage. The address can be your main website URL or even the Community Home page itself. 

Below is the sample format:

<img src="https://community.tribe.so/files/portals/cae/banner_54224.png61" style="height: 25px; margin-top: 2px; background: #ffffff;" /> | https://tribe.so36 | start