Fixed with – change the top logo/visual header

I am very new to WordPress – so forgive me if this is just too simple or obvious once you’ve been around it a while.

I am sure there is a way – guide me in the right direction please, to replace the top “block” on most themes to be my graphic.

I am using the default theme with two colums fixed width. I want to change the block of colour (where I can change the words to display header wording of my choice) to my graphic. And then leave everything below as it is.

This really is my first time at WordPress – what a fantastic community.

Any developers out there are welcome to make contact with me – I have a couple of sites that I want to add WordPress to – and you could help develop that – and you can get paid for it.

Best wishes

Gordon