Every Test comes with an option to "Sweep" or Step a parameter over the entire run of the test. In other words, you can vary a particular parameter for each run of the Test.
For instance, you can Step a particular resistor's resistance from 1K to 10K by increments of 2K for a Transient Test. When you run the Transient test, the first transient run will be run with the resistor's value at 1K. The second transient run will be run with the resistor's value set at 3K, since the increment was set at 2K. Each step of the resistor's value will result in Transient test so the Transient test will be run 5 times, with resistor's values of 1K, 3K, 5K, 7K, and 9K. The combined results will be displayed in a graph.
To set up a sweep, select the test you would like to run from the Test tab in the toolbox and set up the test parameter. Then click on the "Sweep" tab in the Test setup.
see a movie of B2 Spice's sweep capabilities in action