How to readjust header size and also move navigation menu

Hello,

So I am not the greatest at coding and may be a little computer illiterate but I try. I uploaded a custom header image that is 325×90 and when i view the page its ballooned up and skewed. I adjusted custom-header.php from width 2000 and height 500 to 325×90 and nothing changed. Not sure what else to try.

Also I would like to move the navigation menu from the right side of the page to the left. From searching I discovered to change some “floating” option from right to left, but it only moved it a little bit over.

I am using the Formation theme and my website is jpperformance.net(still under construction, and I’m new to this so go easy please!)