I just knew that to create your own customized button, sidebar titles, footer or even header, software called GIMP can be used. I learn to use it by creating my own footer. The result is not bad! I just have to know the width of column and then I can design it according to my wish.
As what has been taught by the Blog U editor, the image than can be saved as .jpeg, .png etc. Next is whether to save it in computer or upload it to free image hosting (I like using Flickr!). To put it into the blog layout, choose add element > add picture or add html. I like.