First, imagine a hole in your wall.
There was a hole here, as you can sort of see, but my overzealous husband started my project for me before I got home so I missed a couple of steps. If you really need to see what a real hole in the wall looks like, pick up the biggest, heaviest picture frame you have and ram the corner of it into the wall. Happy?
Anyways, there were some obvious holes here and they were covered up by wall putty.
This wall putty.
And here is a very blurry picture of a typical, basic, run-of-the-mill putty knife.
Basically, the instructions say to just slob it on the wall and let it dry (cure) for twenty-four hours before you start sanding on it. The instructions also say that when you do go to town sanding on that wall, you be sure and wear a NIOSH-approved face mask because that dust will give you cancer!
So you sand.
Until it's all nice and smooth.
Old t-shirts can be quite handy as damp rags to wipe away dust.
Your holes may still be a little holey and you may have to putty some more, as I did.
Just slob it on, I promise it doesn't have to be perfect.
Slob it on!
Tiny holes = more putty.
Slob, sand, wipe, and repeat.
Repeat until either you lose your mind or the wall becomes smooth as......smooth. Real smooth.