SciFinder lets you combine a previously saved answer set with your currently active answer set. Both answer sets must be the of the same type: reference, substance, or reaction. Click here for more help.
If you are just getting started, you may also want to consult the Research & Writing section of the Chemistry Resources guide which has a quick overviews of the ACS Style Guide and steps in Preparing Your Dissertation.
There is also a good overview of using the RefWorks citation management software.