
Of course, I can at least try to explain :) At first, I just did the regular 500px gif until I thought it was finished. Then I used the Rectangular Marquee to divide the 500px into three 160px pieces because that’s how big they are on Tumblr.

Then you can select the left piece, put a guide to the right side, after that select the right piece, put a guide on the left side of that and then select a piece in the middle so that the spaces between the ones on the side are the same size, and put guides there as well. It should look something like this.

Then you can go and crop a piece, save it and go back to crop the next one. I hope that makes sense :) I don’t know if this is too complicated or if there’s an easier way but that’s how I did it :)