@Caperdeb1952 There are a few options. The easiest is type the first 2 in and then highlight them and then drag the little box in the bottom right corner down as far as you need. Similarly you can use the Home-> Fill -> Series... option. If you type the first 2 in, it will automatically fill in the boxes/options:
Lastly, you can use a formula. But there are lots of formula options depending on what you want to base the calculation on (i.e. previous cell + 14, or fixed date + 2x number of weeks, or ... )
Wait, by "biweekly" do you mean 2x a week or every 2 weeks?