***Here's how you can make a transparent background in Photoshop:
1. Select the Rectangular marquee tool, (Press M for shortcut)
2. Select which part of the layer you want to apply the transparency by dragging the cursor at the image.
3. Then at the Menu, select IMAGE > ADJUSTMENTS > VARIATIONS > LIGHTER
4. You can lighten the image as much as you want.
***Changing Colors.
Again at MENU, IMAGE > ADJUSTMENTS > HUE/SATURATION
Adjust the HUE
This is an easy way to change colors, specially the icons
***Other important tools can be found at EDIT > TRANSFORMATION
Here you can SCALE, ROTATE and FLIP your images
***Play with you image using FILTER effects.
***Use the Smudge Tool its very helpful, the one that copies the color of the cusors immidiate background.
Hope this helps.