The elementary pieces in fastNLO are called "scenarios".
One scenario includes everything that is needed to compute the theory predictions for one measurement - usually corresponding to the results of one experimental publication.

• You need some common code - required for all scenarios.

• In addition, you need specific code for each scenario, together with a table of pre-computed perturbative coefficients. Both can be accessed from the menu on the left.

You can also try the interactive web interface.