This shows a current text widget entry in my blog, which uses the Quentin theme:
<h6><span style="color:#643716;"><em>If you see Google Adsense or other advertisements on this blog, please be aware that I have not placed them here. Any compensation goes to Wordpress.com. I prefer they not be here, but I have no control over their placement. If you do happen to see an advertisement, please let me know, as Wordpress users are not able to see them when they are logged in.</em></span></h6>
Before I added the heading tag, I was able to use the strong tag to bold text. Now, I can't get it to work. If it's not possible, I'll live with italics and not worry about it.