a sole proprietor is never an employee so even if you had employees you would not include your income or pay your taxes through form 941. since you have no employees there is no 941 filing requirement.
you file Schedule C to report your business income on your 1040.
generally, you can avoid penalties for not paying in the taxes you will owe by meeting either of these 2 options
pay in for 2021 on each of these dates (on 5/17/2021, 7/15/2021, 9/15/2021 and 1/15/2022)
a) 25% of your 2020 taxes if your adjusted gross income was $150,000 or less or 27.5% if your AGI was over $150,000
b) 22.5% of your 2021 tax
since most people don't know what their 2021 tax will be they use option a
you make payments by either using form 1040-ES or you can use the IRS website
https://www.irs.gov/payments
if your state has an income tax, it's likely you'll owe periodic tax payments to the state
