Cat pages:Can't put my photos there

I keep trying to add my photos to my cat pages but it keeps telling my files are too big. I am not sure how to decrease the photos from iphoto. I use a Mac.
I looked at the thread above but it doesn't help.

Unfortunately, there's no Mac version of irfanview, but there are some suggestions here

I figured out a better way to do it. The links you provided jcat were a good starting point but the links were older and I have Mac Leopard so I downloaded Resize Me from the Apple store for 20 dollars. You can get a free 10 day trial if all you want it for is for the kitties. I love discovering whole new computer frontiers.
laureen thanks for responding. You are right about having to download and upload not being quick but I love my Mac so I will have to suffer sometimes.