Press F1 for help.
Lookup NPV() or XNPV().
Searching Excel help for "Cash Flow" will also bring up these functions.
__________________________
Discounted Cash Flow in its simplest form is too mundane for a template.
Discounted Cash Flow "templates" span the gamut: 1) from simple asset valuation; 2) to medium level rent/lease decision making taking into account taxation; 3) to complex company valuation models.
If you are going to build the more complex models, give it a shot and post questions. I'd be happy to give you my input. But try and use the help files first for the easy questions.