[R] R Newbie Question/Data Model

[guox at ucalgary.ca]

Given a data set and a set of predictors and a response in the data,
we would like to find a model that fits the data set best.
Suppose that we do not know what kind of model (linear, polynomial
regression,... ) might be good, we are wondering if there is R-package(s)
can auctomatically do this.
Otherwise, can you direct me, or point out reference(s),
basic steps to do this. Thanks.

-james