Step 1 - Starting Out
Create a new 600x400 document with background color set to white.
Step 2 - Rounded Rectangle Base
Click on the "Rounded Rectangle Tool." Once this is selected, change the radius to 10 pixels. Then drag a rounded rectangle shape onto a new layer as seen in the image. Choose the color you want, I'll use a nice blue for this tutorial.
Step 3 - Stroke
Right click the rounded rectangle's layer, and go into it's blending options. Give it a stroke with the details above. It should look like something below.
Step 4 - Removing Round Bottom
Grab the "Pencil Tool" and pick a square brush of about 5-10px. Right click on the rectangle's layer, and hit "Rasterize Layer." This will allow us to use the "Pencil Tool" over the existing shape layer. Next, pencil the bottom right part so that the bottom area is a flat edge, instead of being rounded. Choose the same foreground color you used for your rounded shape.
Step 5 - Base
Select the "Marquee Selection Tool," and make a selection like in the image above. Once the selection has been made, choose a bright vibrant color that has a similar shade of the previous color used, only more closer to white. Fill it with the "Paint Bucket Tool."
Step 6 - Gloss Coat
Make a selection like in the image above one more time. Also, create a new layer for us to work with. Using the "Rectangle Marquee Selection Tool," hold down "ALT" on your keyboard, and drag across the bottom 19/20 of the selection to create a selection like below.
Reset your foreground/background colors by hitting "D" on your keyboard. Next, with the selection still up, click on the "Gradient Tool." Use the "Foreground to Transparent" preset, and give gloss to the upper part of the image. If done correctly, it should look like something below. Play around with the length/distance to achieve various effects.
Step 7 - Soft Light Color Change
Hold down ctrl, and click on the rounded rectangle layer's icon. This will make a selection for us to work with. Create a new layer above the rounded rectangle one. Now with a Black to Transparent gradient, make a gradient selection over the entire rounded rectangle, going from top to bottom. Change the layer's blending mode to "Soft Light," and something like the image below should span in return.
Step 8 - Title Text
Select the "Type/Text Tool," and add some 14px title text to the top of the bar. Make sure it is white, most other colors don't seem to fit in well here.
Step 9 - Extensive Text
Repeat the step above, only with 72px font, and placing it in the bottom right corner. Make sure the color is black, also. I put "Content" to help represent the box as a content box, but you can put whatever you want (the text doesn't have to be 100% aligned, as shown in the next step.)
Step 10 - Deleting the Extra Text
Hold down ctrl, and click on the rounded rectangle layer's icon. This will make yet another selection of it. Now right-click the selection and select "Select Inverse" from the pop-up menu. This will invert the selection making it look like the image above. Next, select your font layer again and then hit the "Delete" key on your keyboard to remove any extras from the font.
Step 11 - Blending Mode
Change the text's blending mode from "Normal" to "Soft Light." This will make the light blend in with the base's background.
Step 12 - Filler Text
Time to add some good ol' filler text to top off this tutorial. It's best to use a smaller font, 12px seems to do the trick most of the time. I used "Lipsum" to represent the filler selection. Do what you want with it, use it in your next template or whatever. It's up to you (obviously -_-)
End! Job well done!