Im on the trial version of SketchUp trying to perform some simple editing/color changes to an uploaded .png file. Im not sure what would be the best app to use (3D, Layout, etc), plus Im not sure what to even use for color and shape editing tool. Im using Windows 3D paint but seems to be a waste.
SketchUp and LayOut are not image editors. If you want to edit a .png file, you should use an image editor. There are many choices out there like PhotoShop and GIMP. I use a freeware editor called PaintDOTNet.