how to install sheet from PC to Musescore

Well, the process of converting a picture of music into actual music is a bit of AI, but there are program that can attempt to do this, with varying degrees of success. Starting point would be to try File / Import PDF from within MuseScore. If that doens't produce satisfactory results, you can try doing a web search for "otical music recognition" software and see if you find one whose features, reviews, and price seem like they would meet your needs, but realize it's always going to be rather iffy, results will generally be no better than voice recognition. Next version of MuseScore will also have an improved facility built in, but still, don't expect miracles.