Look in your browser at the top of the screen and you will see the web address (url) of the ACTUAL post you made. So for example June's crafty place, her web address will be http://junescraftyplace.blogspot.com/ but her actual post she made will be something like http://junescraftyplace.blogspot.com/2009/07/card-challenge.htmlAll you need to do now is click on the web address, highlight it and copy it (control and C). Nip over to the challenge blog and paste (Control and V) it either into their comments box or "Mister Linky" whichever the blog has.
Clear as mud? Have a practice here!
PS.... This takes a little bit of practice sometimes so don't worry if you get muddled up. Ask us anytime for help and don't worry if you get it wrong, you won't be the first and certainly not the last!