You don't need visual studio to create pages in mojoPortal, see the article How mojoPortal Works.
You create a page using only the web browser, just create a new page and set the parent page as your about page. Optionally you could uncheck the "Include In Menu" in page settings if you don't want the page to appear in the menu.
When you create the page note the url in page settings, if you name it "Privacy" then the url will typically be ~/privacy.aspx unless you have enabled extensionless urls in which case it would be ~/privacy
Then in Site Settings you specify the relative url in the textbox for Privacy Page Url (but leave out the ~ and just use /privacy.aspx or /privacy)
Visual Studio is only needed for developing custom features that plug into mojoPortal.
Hope that helps,