Remove artifacts (manually)

update: After waiting a long time, I finally managed to get an image. i now want to render this as a function of frequency. so as a PSD. but i keep getting an error. how can i solve it? I also have a file called " ica picard : eeg ... ( before)" that was created when running the artifact pre-processes. but I assume this is my old image? the PSD does work on that.