For backdoor Roth conversion, should I enter all IRA contributions till 2021 (I did $1000 in 2020 and $1000 in 2021), if I did IRA -> Roth conversion in 2021?

Whether or not you entered the 2020 contribution on your 2020 return you should definitely not enter it as a contribution in 2021.  You should enter the amount of your contribution for 2021.

Here's how to enter a backdoor Roth conversion.