Ok, yes you are doing it correctly. You will need to specify the logo size using custom CSS in the “Default Design Setting” field “Custom CSS”
#Logo a img {
display: block;
width: auto;
height: 65px;
}
I don’t know the size of your logo so you’ll have to change the height value to you logo dimensions.
Can you provide a link and I can be a lot more accurate and specific to your situation.