The first step if you want to print payroll checks from Excel is to find a template. You can easily find these through a web search. The basic templates provided with Excel don't include checks, but you can find useful templates for supporting documentation like timesheets.
Once you've found and downloaded a check printing template for Excel, you input information specific to the recipient and money being disbursed. You save the check as a PDF, which you can then print and distribute to the employee.
Having a check-printing template PDF isn't enough. Financial institutions are diligent about preventing fraud, so you can't print a check on plain paper and pass it off as official. If possible, obtain the requirements from the financial institutions your employees use to make sure your checks won't be denied. These may include paper, size and font specifications.