[Twenty Eleven] Can them use a header image that is..?

This morning, I decided to tweak my site’s tagline to something more specific. My site is called Inspiration Point and here’s the link: https://inspiration-point.org

Originally, I wrote “Come and Enjoy Encouraging Stories.” It appeared under the site’s title. Someone in Internet Advertising suggested having something more specific in terms of defining my niche. I came up with something that fits.

The guy’s other point is to place the title on a header image and modify my image so it’s 100 pixels high. The width is okay. I tried this before and it created a pixelated image. It was done through WordPress.

Just downloaded Picasa. Does my current theme let me do the above? I have to look and see how to use Picasa. I know that I can apply text to images. What’s a good readable font style and size. I’m looking at Arial Rounded Bold.