Direct download via FTP or localhost
Step 1. Unpack archive
If you have an extension that is packed into a zip-archive or tgz-archive, then you need to unpack it locally first. For example, when you buy Magento extensions in our store, you get them directly on your computer. So, unpack them by your favorite file archiver. After unpacking, you will get a new directory which should contain something like this.
Now in this directory go to the Webinse_NameOfExtension folder. You should see the folders such as app, js, skin and other one.
Step 2. Upload files
The next step is to upload all the folders of the extension excluding package.xml to your store root directory using your FTP. If you are installing extension on a localhost site then copy all the folder to the root directory where local site is located.
Step 3. Activate the extension
After the files are downloaded successfully, you need to go to the admin panel to activate the extension. In the Magento Admin panel go to the System -> Cache Management. Click on "Select All", select option "Refresh" from drop down Actions menu and then click on "Submit" button. After these steps, log out from Admin panel and log in again.
Step 4. Check extension in configuration
The last step it is necessary to make sure that the extension is installed in the system. Go to the System -> Configuration. In the "Advanced" tab, select "Advanced" section. Expand the "Disable Modules Output" group and find the name of the extension that was installed. Check that your newly installed extension appears in the list. If it does, it means that the installation was successful. Now you can use the extension!
Installing an extension from Magento Connect
If you want to install an extension from Magento Connect you can do it. Go to the extension page on the Magento Connect site. If an extension isn't free, it must be purchased.
Click on the button "Install Now".
Click on "Agree to the extension license agreement" checkbox.
And then copy install key.
Go to the Magento Admin panel of your site. Now go to System -> Magento Connect -> Magento Connect Manager. You must re-enter your Magento Administration Credentials in login form. Because only administrators with full permissions will be able to log in.
Paste extension key from Magento Connect into the input field to install extension. Then click the "Install" button and the extension will be automatically installed.