I'm no Texturing Expert however i did learn a few tricks to make a metallic texture. The tutorial i read was hard to follow.
If your anything like me you probably don't like rereading the same step 5 times , scratching your head going "zuh??"
So i'll try to make an effort to make this easy to follow. We will be attempting to generate something that resembles this.
Ok let's get cracking!!
Alright usually i make my textures at 512x512 this offers fairly good resolution, but not too horribly big to bog down the filesize of your product.
So Create the Texture Go File -- New -- set width and height to 512 and hit ok. I usually make the bottom layer black for this step.

Now make a new layer.
Good! you should have two layers now.

Next we want to create a Gradient. Make sure your Foreground and background colors are white and black.
Now right click on the Paint bucket tool and select gradient.

Now we want to drag a line across the image to create our gradient. You can play around with the gradient styles up top near
the menu. but we want to make something that looks somewhat like this.

Success! great job! But this doesnt look like metal. Lulz most tutorials ive seen end it here. WTF OMG! ok ok...
Let's continue
Now we want to add some lighting effects. Now go to Filter - Render - Lighting Effects.

You can play around with the lighting a bit to find something that best suits your needs. For this tutorial im just going to use a basic spotlight like so.

Which makes it look like so.

This still doesnt look that metally yet.. but we still have a long ways to go. So now lets add a new Layer.

Now we want to set the Layer Blending to Overlay. To do this go to the layers window right under the tab you'll see a
drop down box. Normally it will say Normal. Click that and set it to overlay. Like so
I know in the shot i made my layer white. I recommend using a darker color like Medium grey or even dark grey on this layer. Otherwise the whole thing comes out way too bright.
Now we want to create a weather effect. Go to the Layer Window and click the channels tab. Down at the bottom of the window there will be a small button that says New channel. CLICK it like this
Now we got a new channel which should look completely black. Now we want to make some noise, So go turn on your Stereo full blast and give the Old man next door a heart attack.
Wait not that kind of noise oops. Ok go to Filter - Noise - Add Noise.
Make sure to set the Distribution to Gaussian and check Monochromatic. Set the slider bar to a moderate amount of noise. I usuallu use somewhere between 6% - 20%.
Now select the Paint brush tool, set the color to Black. Set the Size to around 20 or 30'ish. set the opacity to 10 - 30%. Now randomly paint out the specks to make
some areas that look speckled and some that aren't. somewhat like this.
Once you got a decent distribution of Speckles, It's time to select it. You can drag the channel down tot he button at the bottom of the channel window. Here
Now go back to the layers tab and make sure the Top layer is highlighted. Click on the gradient tool and drag a line across the page. depending which way you made your gradient on the bottom layer may affect the way this looks. so you may need to play around with this to get it to look right.
Anyways we want to get it to look something like this.
Cool now we have some Tarnish. But the Fat lady hasnt sung yet so lets continue.
Ok we got A somewhat metallic look to it. But it still lacks something..
Next we want to create another layer again.
And set that layer to overlay again
Now we want to give it grain. Like most metal its cut into sheets or has been sanded to give it that grain effect. To achieve this. Go to
Filter - Render - Clouds You may need to redo this step a few times until you have a nice even distribution of white and black.
Then we wanna add some noise again..
Now we want to Distort it, so go Filter - Distor - Polar Coordinates Make sure to set it to Polar to Rectangular.
Nice! One Last step is to take the eraser tool Set the Opacity down to 10-20% and erase random areas.
Also you can go through the layers and change opacity, brightness, contrast and even color to make the metal seem more realistic.
Another trick also is to select the Line tool and paint black lines all over the texture. Then using your eraser tool erase random parts of the
lines to create a scratched Metal Effect.
Also if you want another good grain effect. Add a new Layer
Set it to Overlay
Create the clouds again
Add noise again
But instead of going to Distort. This time go to Filter - Blur - Motion Blur
Set the Angle straight up and down and hit OK. Use the eraser to take our random areas. This was my Last step which gave me my final texture.
I hope this tutorial has helped you get a decent Understanding of how to create a metallic texture.