ms project, post production

[iknowu99]

i am using the microsoft project software (i know it's not excel but seems like excel savvy would help). When seting up the project i find that it is easy in my case to set up project information with shceduled from project finish date. so in this case everything is backwards.

my question is how does one setup some post project tasks? i tried negative duration but it wont accept it.