Computer help again....?

My monitor looks grainy. Am I in safe mode? I did a search, another person has the same problem but they did not receive an answer. My computer freezes up every great one in awhile, I have done the anti virus scan, ran Mawwarebytes....tools deleted history...Read to press Ctrl+Alt-del did this, a window opens reads with a shaded background in blue Safe Mode osd not responding blue screen. WHAT in the hell did I do? Computer is running choppy like, monitor is grainy, computer freezes up. I am illiterate on a computer (not into computer but need it) how did I get myself into this mess, how do I clean it up? Thank You very much for your time and help.