I joined the Janaazah Salaat after the second Takbeer.

Answer

In this case the musalli should recite the third Takbeer with the Imaam, then the Masnoon Dua, then the fourth Takbeer. After the Imaam makes the Salaams, recite one Takbeer and Thana. Thereafter, recite another Takbeer and Durood Shareef and terminate the Salaat with Salaam. However, if there is the fear that before completing the Salaat in this way, the Janaazah will be removed, then recite only two Takbeer and end the Salaat. Omit Thana and Durood Shareef.