Yes that is correct, but you can add a different size if you want. First figure out the size of the image you want to upload, then go into your functions.php file and change the header size to the exact size of your image, then upload it to WordPress (as you’ve already done).
Some users upload a smaller image in their css to show when viewed in mobile browsers. You would add something like – background-image: url(your-image-link) !important;
and
background-position: center;
….if you wanted to do that. If the logo you have works fine enough then you can just leave it as it is.