Adding Pages in Musescore

Insert a section break and/or Page break https://musescore.org/en/handbook/breaks-and-spacers

If they are already written as separate scores, easiest thing is to export them all as PDF's then use a tool like pdfsam to combine them.

If you haven't written them yet and are OK with them being more or less permanently connected in a single file, you can do that, add section breaks / page breaks, and new text frames for the titles.

Hey! If you are talking about adding a cover page then change the view to page view, and then drag the text box to the bottom of the page and it will move your measures over to the second page leaving you with a cover page. To add another blank page, simply click on the first measure>add>vertical frame, then change the size of that frame to make a new blank page. You can do this as many times as you want.