Google Sitemaps

[SEO]

Hello friends, My Sitemap was created a few years back and now I've got a few pages renamed and some new pages added as well. As my Google Account prompts me Warnings would you please guide me though the process of resubmission my Sitemaps with needed changes? Should I just change my Sitemaps in Notepad and to reload it on my public server or should it be done by letting Google know about my changes on order the right pages be indexed there? With much thanks, Michael.