Hi Trynity!
1. Open the image
2. Click into white area with Magic Wand Tool
3. Shift+Crtl/Cmd I
4. Go to Paths palette and click small arrow on the right up corner and select Make Work Path.
5. Choose Custom Shape Tool and Edit > Define Custom Shape
6. Give a name for your new custom shape.
7. If you like to save it look up to the menu bar. There you see it's written Shape and the image.
Click small arrow on the upper right corner and choose Preset Manager.
Select the shape or shapes you like to save as a set.
Choose location for it. It don't need to be on your hard drive. I'm having a Photoshop extras folder in my external hard drive and just load the things when I need them.
The Photoshop is working quicker when I'm not keeping so much stuff in it's folders.
When you draw your custom shape you maybe wonder that it's only having the outlines. Then make it as a selection by clicking down from the paths palette Load as a Selection and use Paint Bucket Tool to color it.
Here is also a custom shape I made for you.
Some tutorials of custom shapes:
http://www.biorust.com/tutorials/detail/48/en/
http://www.myjanee.com/tuts/shapes6/shapes63.htm