What is the order for bleeding the brakes on a 1989 900s saab?

The 'Standard' order for bleeding hydraulic brakes on any vehicle, Saab or otherwise, is to begin at the wheel that is farthest away from the brake master cylinder.

typically the master cylinder is on the driver side firewall of the engine compartment. Start bleeding at the passenger side rear wheel. then work your way forward:

passenger side rear
driver side rear
passenger front
driver front

Do yourself a favor and buy a brake bleeder kit so you can do this solo and alspo buy a can of PB Blaster and spray on the bleeder screw fittings a couple days ahead of actually doing the work.

Start with wheel furthest from master cylinder,then 2nd furthest,etc.,closest wheel last.