Logo Size

Hi there, I am having trouble uploading my logo. Every time I do, the logo is much bigger than it should be. I have reduced the size of the logo in Photoshop to try and make it fit, but no matter what size I make it, it uploads as the same size, much too big. I want it to be the same size it is in the template preview. I could not find the dimensions for the size the logo should be, but as I said when I resize it doesn't make a difference. Please help! I apologize if this is a dumb question I am new to Wordpress. Thank you!