[plt-scheme] Newbie problems with leftparen and **

Does anybody use the leftparen framework?

I started to work on a tutorial on writing servlets in Scheme (http://
tprimke.wikidot.com/scheme:servlet:tutorial) and I'm trying to find
out what the ** function does.

For example, I know I can use it as follows:

(** '(p "Hello, world!"))

to get the "<p>Hello, world</p>" content, but how could I get a link
like "<a href="some address">Some text here</a>"?

Besides, evaluating

(** '(p "Hello, world!"))

gives (group (p "Hello, world!")) on my PLT Scheme 4.1.5. I can't find
out what this group form is.

Sorry, if my questions are lame, but I'm quite a newbie Schemer and a
newbie servlet developer.