When you want to use your logo on your website, you'll want to Export it. Click on the "Export" menu.

You'll find that you can export as a Jpeg, Gif, PNG (transparent background) and even PDF format.

If you choose the "More Export Options..." you'll have see more options that will give you further flexibility.

You'll find that you can set the Width and Height of your image:

You can also resize the "logo canvas" as seen below. This will allow you to set the size visually.

When you click and drag to resize the logo canvas, the logo also resizes....