BuddyPress cropping avatar

Users who do not have compatibility view enabled in IE8 can not crop their avatars after registration or from their profile. I came across this thread:

http://buddypress.org/community/groups/how-to-and-troubleshooting/forum/topic/default-crop-avatar-selection-is-not-working/?topic_page=2&num=15

One of the solutions was to do this:

1. Download Jcrop (http://deepliquid.com/content/Jcrop.html)
2. Put the jquery.Jcrop.js file on your server in your theme /js folder
3. Link jcrop in your header.php in the header

I have done step 1 and 2, but have no idea how to do step 3 in my header.php. I had a look at their website, but it is over my head and I am worried about interfering with my theme in that way.

Please could someone help me on how to link that file in my header.