You can contribute up to $7,000 for 2021 if you do it before April 18, 2022.
You cannot contribute retroactively for 2020.
If you are self employed you do not have to pay yourself via a W-2. You can contribute to an IRA based on your net self employment income. You can also contribute to a SEP IRA up to 20% of your net self employment income if you wish in addition to your Roth IRA.
