Depends on whether you are using RoboHelp HTML or RoboHelp for Word and which version.
Please see Before You Post.
Based on your post re the TOC pod, I'm assuming we are still talking about RoboHelp HTML 8. See http://www.grainge.org/pages/authoring/rh_tour/index.htm and look under RH8 New > Tables.
You can either define the cell formatting there or do as I do and apply styles from the style dropdown.
Beyond that, can you be more specific about the problem?
See www.grainge.org for RoboHelp and Authoring tips