Ummm... nevermind. I misread your comments and thought you were trying to do something else. Here are the proper steps:
Steps:
1 -- open the file in Photoshop
2 -- create a new layer above "layer 0" (which contains the original PNG), and name it "match"
3 -- using the pencil, paint in a small spot of the #33ffcc color on the "match" layer. This is just for matching later.
4 -- duplicate "layer 0", and place it between layer 0 and the "match" layer you just created in step 2. Rename the layer "copy" just for clarity's sake
5 -- select the duplicated layer, and then adjust the colors using Image > Adjustments > Hue/Saturation until it nearly matches the color you are looking for (the blue circle includes a gradient, so it won't be exactly #33ffcc). Compare it to the #33ffcc in the "match" layer. This will mostly be done by adjusting the "Hue" slider. Make sure that the "preview" checkbox is on, so you can see what your changes will look like.
6 -- once you have adjusted it to your liking, do a Save for Web
Make sense?