Step 1 - Starting Out
Create a new document. I will be using 500x100 in this example. Select the Elliptical Marquee Tool (M) and create a 75x75 circle marquee.
Step 2 - Filling the Circle
Create a new layer, and then on that layer fill in the base of the circle by using the Paint Bucket tool, and filling it with a nice maroon foreground color.
Step 3 - Moving the Marquee
Next, on the same layer, select the Move Tool (V) and hit up 5 times on your keyboard, and right 5 times on your keyboard. This should position the Marquee 5 pixels up and 5 pixels to the right of the maroon circle you just made.
Step 4 - Moon Shape
Hit the "Delete" key on your keyboard, and it will delete that part of the circle which, in turn, creates a moon-like shape.
Step 5 - Transforming the Layer
Duplicate the moon-like shape layer, and then go to Edit»Transform»Rotate 180º to rotate the duplicated layer 180 degrees.
Step 6 - Finishing the Logo
Position the new layer so that it overlaps the previous layer to make our header's logo. See the image for what it should look like. Kind of like a biohazard logo or something.
Step 7 - Text
Select the Text Tool (T), and then choose the font "Century Gothic" with a 48pt size. Type text out, and reposition it so it is in the center of the logo, but to the right of it. Next, highlight the secondary word (or half of the word if the logo is made up of only one word) and change the text from regular to bold so it sticks out more.
Step 8 - Gradient Finish
Click the background layer. Next, make your foreground color a light gray color. Now give the background some gradients to offset the image color, making it have a nice feel.
End! Job well done!