So this is pretty easy but might be complicated to some.
Download this Image: http://gamescenter.ucoz.com/other/game_frame_blank.png

When you have done so, open it on your photo-editing software (recommended photoshop), and follow the instructions below:

Make sure the background is transparent!

1. Open the image given on your image editing sofwtare

2. Find an image your want to use as the game logo and place/paste it onto your image

3. Resize the image you have placed onto your our image

4. ^^ Antil it is placed how you want it to show

5. Now move the logo to the bottom layer and put the image we given you to the top but select the logo

6. Now zoom in, and arase the outside of the frame on the image we given you including the edges - make sure you still have the logo you found selected!

7. Now when you have done that - move the logo your found to the top layer

8. Here is what it should look like (this is an example - your logo should be different)

~Done if you have a white background on your site
If you have a dark background keep reading.

9. Zoom in and put erase the outside white parts of the logo we given you (make sure its on the bottom buts its selected)

10. You dont have to remove the gray part/the shaddow if you dont want to but you can if you want. When you have done this is what it should look like

Then its ready for uploading as the game logo

Edit: Sorry its messy I was in a massive rush