How to change the logo icon

Hello

Sorry I'm really struggling to work out how to change the logo icon in the header.

I've downloaded the new icon to

wp_admin/images
wp-content/themes/images
media

and none seem to work. each time I think I've downloaded it I just get the name of the website http://reflexologyinbrighton.com/

Appreciate your help, feel like it's an obvious mistake but can't figure it out!!!