We installed the paintover tools, which have everything you need to be able to do crits with feedback, or even make digital art for fun. Here is your link: http://www.conceptart.org/graphiceditor.php
You can also find the link in the upper right hand corner of the box shaped toolbar below the header banners, where it says "paintover and critique tools".
a. right click on the image you want to crit or paintover, and copy the image URL (for the Mac folks you just want to get the image link). Paste the URL into the tool link and it will load instantly. You can also start from scratch, or upload from your computer.
b. paintover or create if you want to.
c. You can share the helpful results of your paintover and crit by making a new reply and uploading the image.
d. Get much respect and thanks for being awesome and constructive.
***IF you encounter the one bug I found, which is your saving the image leaves a file without the .jpg extension, simply rename it with .jpg at the end, and you should be good to go.
Hopefully that will be useful to you all as we work to improve the quality of critiques and ability to do them well, all right here on CA. Here is a quick peek. You can also work from scratch, which is shown below too, if you so choose.