This is fairly common job for the E36 crowd.  The old one will get brittle from UV exposure.  It comes in two parts.  First mark the wiper position with tape.  Then remove them.  Take the little cap from each arm and there is a nut inside.  Next, remove the fresh air vent inlet cover from the center of the cowl area.  It has a rubber gasket around it, pull it off and the cover pops out.  The cowl covers will have a few plastic caps with a scerwdriver slot in them.  Twist them out.  The cover then just pull off, they may slide a little each way to release some retainer clips on the back.  Transfer them to the new ones and work backwards.  I took me less than an hour. 
Beware the sight of the mighty 1.8!!!!