Can't tell what kind of coin it is. Different methods, depending on coin type. I can't tell scale of coin either.
Yeah, I know, you are just getting started, I don't want to come off as harsh. Sorry.
I think that it is wheat cent, slight powder green edge makes me think that. If so, I use a toothbrush, if that doesn't work, a brass brush. I figure that they are not valuable, so I can't hurt them. You can also boil coppers in peroxide to remove the trash, but it removes the patina too.
Oh yeah, welcome to TNet and good luck!