Gimp - http://www.gimp.org/downloads/
Open up Gimp, then go to file, new file. Now go over to the Image Size and make the pixel size 1600 by 1600 pixels. Then click Okay. we're making the image quite large so that when it's uploaded to youtube it looks higher in quality than if you were to just upload it in the default 800 by 800 pixels
Now we're going to just look at what tools we have at our disposal to make our icon. So go to the main window, click windows, then click layers and click toolbox. You should get two new windows. Now in order to edit the picture itself we are going to go onto layers, right click the layer that says background, and click remove alpha channel (if it's already removed for you, then you're fine)
So we're just going to use the circle select tool. Make it so it fills the entire image. Then click select. Shrink. And shrink it by about 100 pixels. Then click border and make that about 50 pixels. Then use the gradient tool, select bilinear, and find a small black to grey gradient or really whatever colors you want to use. After that just drag from the center and boom, you got a metal ring.
now we're going to fill in the middle with some green, with the fill tool. Then we're going to add a gradient to that, so select that with the select by color tool, and just wait a while until it's selected. Then select your gradient colors. Then double click the gradient tool, and set it to radial. Then drag from the center out.
After that we're going to add some text, so just add a text box. Then we're going to select it and double click the text tool to open up the text editor. Then I'm just going to select a font that makes my letters look pretty good . Okay so once I've done that I made my font about 800 and you want the font to be black because we'll color it later. Then we're just gonna right click the text layer and click select by alpha. Then go into layer and click crop to selection. Then click the alignment tool, and click the text you created. Go back and double click the alignment tool and center your image. Once that's done click select none. Then go back to layers and right click the text and select expand to image size. Duplicate your image, make the layer on top invisible, Then select the bottom layer and click filters, blurs, motion blur and select zoom. Then you're going to use the measuring tool to measure from the vanishing point to the left border of your image, and input that into the x coordinate, then measure from the top of your image to the vanishing point and that will be your Y coordinate, uncheck the box that says blur outward, set the blur radius to 30 and click okay. Then use the select by color tool, and select the blank part of the layer. Then go to select, click invert. And after that select your gradient colors, double click the gradient tool make it linear and create the gradient.
Then make the top layer visible, right click it and click add to Alpha selection. Then fill it in with any color. After that go to select, shrink, and shrink it by about 8, and then you can fill that with whatever color you want or use a gradient it doesn't really matter, And just for extra measure go to select, shrink again, shrink it by 10, make the border 1, and fill it in with any color. Then click select none. And click on the background layer in the layers window. Then use the circle tool, and select a rough circle around your green gradient. After that double click the paintbrush tool, make sure the brush is hardness 100, size 5, and dynamic off. Then select your color. Now click in the selection with your paintbrush then hold shift and click on another spot. This creates a straight line with your mouse. Repeat this multiple times for a lightning or branch effect. After you're done you can click select none, then select by color the white part of the image, then right click the background layer, and add an alpha channel. Then go to edit and click clear
Once done you can save it and export it to youtube. It could be exported as a .jpeg, or .jpg. However, the .png has the best quality. Now go to your channel page, go to your icon, and click the pencil. Then it will take you to your google + page, and from there you can upload the picture you created. Remember to upload the ,png and not the ,xcf, The .xcf is the gimp file, not the saved picture.