putting logo on website

I am following a video about building a website with Word Press and want to change the stock logo to my own.  I created one on a transparent background from some shadowed text, and I use as a watermark on photos or videos.  

In the video example, I'm following he gets a logo from Photopea and makes the background transparent.

When I first shrank my logo and tried upload it didn't work, I think becasue it was .PSD.  So I flattened and made a jpg, but when I replace the logo with mine, it has a white background and I see no option to make it transparent.