Workflow/Parking in F-03

HI,

I am trying to see if i can bring a Workflow Process for Transaction  F-03 (restricting the Users and  make it go  through an Approval Process  to clear more than say  $100).. I understood that  i would need to have the Parking Functionality for this  but i do not seem to find a way to gring this Parking or the ability to hold the documents from Posting .

Any suggestions /tips would certainly help.

Thanks

Ram