I've decided to install power windows and power door locks
to my subaru legacy(-94 dl) from my older legacy(-89 gl).
Have any of you never done that?
How difficult it is?
Do I have to do much electrical installation?
Are there already wires or do I have to install new wires?
Do you have any pictures to help me?

Do you even know that the parts will fit mechanically? I'd think that with the different years and body styles things will not be the same. The electrical stuff is a whole other matter. Practically speaking I do not think you will be able to do this.

good luck... you might have better luck installing aftermarket actuators for power door locks and aftermarket window motors... but even that is a daunting task... I can install them, but I am an experienced installer...

hmmm.... I think they would fit. I'm not sure but these two cars look almost same. There are only little face lift. Interior for example looks just same.

Take off the door panels and take a look at the window mechanisms and what wiring is in place.