From VS menu bar you can select Project -> Project properties(on the bottom) and then go to Resources tab. From here, you can add the resource(s) from disk, by hand. Then you can access them from code like this:
PictureBox pb = new PictureBox();
pb.Image = Properties.Resources.NameOfResource;
Don’t forget to set the rest of PictureBox properties like Size, Location and so on …
solved A picturebox import issue C#