You should choose the pay frequency that best fits your business needs. The pay period you choose is up to you. Most businesses pay weekly, bi-weekly (every two weeks), semi-monthly (twice per month), or monthly. You should be consistent over time and across your workforce. i.e. If you pay one employee bi-weekly, it makes sense to pay all your employees bi-weekly. If you start the year paying semi-monthly, it is best to pay semi-monthly throughout the year.
You can choose the pay frequency when you create or edit an employee. The default is bi-weekly, but you can also choose weekly, semi-monthly or monthly. When you create a pay stub, the system will guess the pay period and pay dates based on the pay frequency of the employee and the previous pay stub. You may need to adjust those dates. You will find the pay period in the top left corner, just under the employer information, and the pay date on the top right, under employee information. Just click the dates to adjust them.