Sure, you can post your screenshots on whichever site you want. :3
Just a little note - you can actually take screenshots with your game client by either pressing "Shift" + "P", or the "Pause" key near the top right of your keyboard. The screenshots you took this way are stored under http://myu.icyworlds.net/gallery - that way you don't have to upload them to TinyPic (you're welcome to link to them directly - to get the link, just click on any of the screenshots in your screenshot gallery).
Toby