The Excel options are either in Excel's preferences, or in the Tools menu. Excel 2008 does not come with Solver - you have to download it from the Frontline web site. If you go to Excel help files, there's some info about that. The web site is here: http://www.solver.com/mac/dwnmacsolver.htm
When you download Solver, just follow the instructions on how to use it, and where to install it.