If You want to update from Quick.Cms.Lite v2.0. Check changes using Total Commander. Select file in Quick.Cms.Lite v2.0 (first column) and the same file in Quick.Cms.Lite v2.1 (second column) and click in menu "Files" > "Compare by Content". You will find changes made by us.
HOW TO UPDATE FROM v1.x? You must first update to v2.0 and after to v2.1 Read this: http://opensolution.org/Quick.Cms/forum/?p=readTopic&nr=261