To make sure Installation went smoothly go to “System->Configuration->Advanced” and disable modules output. Check that your newly installed extension appears in the list. Extension name should be like that: Companyname_Extensionname
Also check whether that particular extension is Enabled or not in the dropdown associated with the name. If it does it means that you did everything correctly and you are ready to go.
If you don't know the extension name, you can find the extension name inside extension files. After extracting your Extension, just go to ‘app/etc/modules’ inside your Extension folder, there is a single file by the name like Excellence_Sampleextensionname.xml. “Excellence_Sampleextensionname” is the name of your Extension.