Hi, my compnay has an intranet web site which used to be edited and managed using Contribute. Can i upload the exisiting webpage to Muse and edit using Muse?
No, only Sites, done with Muse can be edited in Muse. As I don´t know conrtribute, you may try either Pinegrow to edit your site or Dw, if it is kind of html only. Otherwise you may rebuild the website in any websitebuilder.
Pinegrow is able to "read" html sites and use almost everything (at least in all of my cases) even scroll motions and so on.
Also Pinegrow is a one time fee and no subscription and if necessary kind of an CMS is available, too.
Muse was a site generator, not a code editor. And like Contribute, Muse is discontinued now. So that's no solution.
Contribute was a poor man's HTML editor. Early on, Contribute was used by Dreamweaver developers so clients could maintain their own sites cheaply. But that party ended when WordPress became popular. Contribute officially ended in early 2017 although it died off way before then.
Assuming you can work with code, you could maintain your site a bit longer in any decent code editor.
-- Adobe Brackets (open source) - http://brackets.io/
-- Adobe Dreamweaver CC - https://www.adobe.com/products/dreamweaver.html
-- Pinegrow - https://pinegrow.com/
-- Visual Studio Code (open source) - https://code.visualstudio.com/
Ultimately however you should get a new site -- preferably one built with WordPress or some other online CMS.