The easiest way is to capture it from your agency's website.
- Open your agency's website and find the logo, usually at the top of the home page.
- Windows: press Windows + Shift + S, drag a tight box around the logo, click the notification that pops up, then save it as a PNG.
- Mac: press Cmd + Shift + 4 and drag a tight box around the logo. The PNG lands on your desktop.
- Choose that file here.
Crop close to the logo: any space around it makes the logo look smaller in the header.