The link Tharashasank provided should work.
For completeness, here is the full Tableau help article >> Change the Name or Logo
You will need to amend the file path from 9.3 to 9.2 (and check the file paths are correct, you may have installed in a different location!!)
If you follow the steps which were in the article posted by me you will get the same results.
Which version of Tableau you are using.
I am using 9.2.4
No need to worry about that. you want different background color for logos right?
It will be done automatically from tableau.
Note: The background colors differ in the two locations, so your logo may look different depending on which location you are viewing.
Please use this steps in your cmd. put your logo or image in C:\My Pictures\logo.png
The image file you use should be in GIF, JPEG, or PNG format.
To change the logo on Tableau Server:
1. Open a command prompt as an administrator and type the following:
cd C:\Program Files\Tableau\Tableau Server\9.2.4\bin
2. Type (for an image up to 160 x 160 px, but not smaller than 32 x 32 px):
tabadmin customize logo C:\My Pictures\logo.png
3. Restart the server for the change to take effect by typing:
4. To restore the default logo type the following:
tabadmin customize logo -d
5. Then restart the server:
If you dont have that site option dont worry.
start from the step 2:
2. Go to Settings.
3. Select the image or GIF you want to use.
4. Click "save."