There are two way to do this. One is to use the built in support for user
definted reports. It is called Report Builder. It is getting a facelift in
RS 2008 and if you are just starting into using RS you might want to check
that out. Otherwise, look at it in RS 2005. I haven't used it but
essentially you build a report model that the user then uses to create their
own reports.
Otherwise, if you don't want to use this then you would have to create your
own RDL (report definition language). It is non-trivial but possible. I know
of people who have done this.

Signature
Bruce Loehle-Conger
MVP SQL Server Reporting Services
> We want to embed reporting capabilities into a web application where the
> user can select the columns they want in a report and build a where clause
[quoted text clipped - 5 lines]
> build a report with SSRS given a dataset. Is this possible? Am I even
> taking the right approach for this problem?