How to resize section heading images?

Hiii all, I've been trying to add some cool Windows XP style headings to my profile sections, but can't figure out how to fit the image correctly. I'm not sure if I should try to resize it using the code, or resize the image itself to fit the dimensions for the box, and then add it. But again, I don't know the dimensions I'd need to resize the image to in order for it to fit correctly. Pls halp Dx

This is the code I'm using at the moment:

.profile .blurbs .heading,

.profile .friends .heading {

background:url(https://i.pinimg.com/originals/15/5b/cd/155bcdaaed18d34a93c6e558d7caa42f.png);

}