adding a welcome message

Folks, New to wordpress, still planning my blog. Did some research on the various themes. I would like to have a static message on my home page like an introduction or welcome message (looked at devian and couple of other themes). Any suggestions on accomplishing this. I noticed that while there are widgets for the sidebar to add text boxes, nothing for the main page. Similarly, can you also suggest how to add tables or some grid on the main content.

Thanks