So the new bill congress passed bumps up the Child Tax credit by $1000 that you can obtain this year, my question is, how? What if I have already filed?

The increased child tax credit has not been signed into law yet.  The House of Representatives is still working on the new stimulus bill and after they get finished it has to be signed into law by the President.  That CTC is not for 2020;  it is for 2021.   When and if it all passes and becomes a law we will have more information on how and when they will implement it.