Designing a template is a lot of work - most of it methodical, fortunately, but it takes a lot of time.

Looking at your image, it would appear that you also want some considerable additions to the standard template functionality, in which case, your template will involve considerable PHP code alterations/additions.

Generally, style elements such as rounded corners and vignette backgrounds are done by building appropriate jpeg images, and controlling their appearance and positions via css.

... but you will have plenty of work on your hands with your proposed structure, and I can't immediately think of an existing template that comes close to your structure.