First, pay attention to the menu options under which you are trying to install these. If the file begins with a "mod", then under the Installer tab click on "modules" (not mambots or components). If it begins with a "com", then try the components option under the Installer tab. If it does not give you a clue in the file name, you can just try all three options to see if one works, or go back to the Joomla extensions page and check to see how it is listed--as a mambot, module, or component.
Second, some of the extensions need to have the initial zip file (exactly as you downloaded it) uploaded via the installer. Others have another zip file inside the initial zip file (that you can see in the folder created when you extract the files), and it is that inner zip file that needs to be uploaded via the installer (and remember, uploaded under the right category--component, module, mambot). By the way, when we say uploaded here, we are referring to the button inside the Installer section that refers to uploading and unpacking. If you need further help with your Joomla software, the information and forum at Joomlaya.com might be of help.