I’m finally beginning acting on my lifelong dream to familiarize myself with renovation. I’ve begun renovating a small room in my parents’ basement, below a set of stairs. The room is eventually going to be a small pantry for food storage and the like. Mother wants me to apply tapestry to the walls after their surfaces have been properly polished.

I’ve removed older bits of loose drywall in certain areas of the already existing walls and simply smudged them over with new compound. I am a little unsure of what the type of drywall compound I’m using is called in English, but it’s quite fine with smaller grains and also quite easily applied.

I’m using a random orbit sander to polish the walls. I do not know if this is acceptable or not, but I’ve heard it to be a fantastic beginner tool, at least when working with wood.

TL;DR:

The walls dried within two days. When I returned to my workspace I found brownish stains on the new walls. Could it be signs of increased levels of moisture on the floor plan? I assume this isn’t preferable...

Does anybody have any tips or advice for a newbie do-it-yourselfer?