How to get rid of or change the 'My Blog' at the top of my blog

Hi there,
I’m just completed my first post and everything looks great – I LOVE this theme! I’m just wanting to know how I can get rid of or edit the words ‘My Blog’ that are at the top of the page. They sit over a very pale image of what looks like it might be a keyboard. I’d like to get of that also. Thanks.