Resize Image in Header

Hi there,

First, do you know how to resize the image (logo) in the header in order to make it much wider?

It is so small in the default size.

In functions.php i didnt find something for the logo

Second, there is a lot of space between the Logo and the beginning of the header. Is it possible to make that space smaller? Ive deleted the “Latest Posts” thing in the header, so the black bar in the header disapeared. But there is some white space between the header logo and the top of the page. How do i make that space smaller?

Thank you