On your twitter account you will be able to create your own personalized header image just like on Google+ or Facebook. With new twitter profile pages your avatar (profile picture) will now appear in the center of your header image.
Because it is for PROFILE head image … you do not have to run and create brand new image right now, mostly people just check for their news feed. However it is nice gadget for your brand.
So if you like to try it go to your “Me” on your twitter page, choose “Edit profile” and then “Design” from the options.
Next scroll down and choose “Customise your own”. Here you have two options to choose: “Take Photo” “Choose existing photo” where the first one will allowed you to take a new photo with your camera and the second one will allowed you to choose from your library of images.
Once you have your image, you can move and scale it but you need to remember that original photo size can’t exceed 1252×626 pixels (with a max file size of 5MB). There is no minimum size, but anything smaller than 640 pixels wide will likely look bad.