Okay, so Picnik is closing in April, but I *think* will be available through Google+. I'm just not super hip with G+ yet, so I haven't signed on. I am making all my banners now, and saving them in a file. You may want to do the same.
(printable instructions click here)
First go to www.picnik.com
Click get started now
Click Upload Photo
Upload the banner template (760px X100px)
You are in the EDIT Folder. Look at the toolbar and choose EFFECTS
Scroll Down the Left effects until you see TINT
Choose the desired color
You can continue to scroll down to TEXTURE to add a layer of texture on the template
Next look on the tool bar and choose TEXT
On the top left, type in what you want your shop to be
Then click ADD
The text will appear on the image sometimes way huge, and white.
You can change the font color and size...and then scroll down the left bar clicking on different
fonts until you find the one you like.
Repeat with any taglines you may wish to use.
Now, if you want to add even more texture, click STICKERS
If you right click stickers, you can do things like send it to the back even behind the texture if you
When you are finished, click SAVE AND SHARE folder
Save to your computer into your prefered file.
Now you are ready to upload your shop banner.
Once you sign in, hover over “Your Shop”
Choose Info and Appearance
Next to Shop Banner Image, Click Choose File
Find your new banner in the folder you saved it in and upload.
Admire your handiwork.
Here are a couple I made myself.