Snowflake – change image size

Hi. On the front page there is an image that i would like to make a bit smaller (santa in the background) The picture is located on top media, but as i cant find it in my media libary i cant download and resize it. Secont question: Is there an easy way to make the page a bit more narrow, or resize it? As for now the theme is so big that you need to scroll alot.