How to: Enable GZIP Compression to Speed Up Your Site is easy!
To enable gzip just Copy and paste the following code into it before the # END WordPress line.
# Enable GzipAddOutputFilterByType DEFLATE text/plain AddOutputFilterByType DEFLATE text/html AddOutputFilterByType DEFLATE text/xml AddOutputFilterByType DEFLATE text/css AddOutputFilterByType DEFLATE application/xml AddOutputFilterByType DEFLATE application/xhtml+xml AddOutputFilterByType DEFLATE application/rss+xml AddOutputFilterByType DEFLATE application/javascript AddOutputFilterByType DEFLATE application/x-javascript
If you are using WordPress and just want to add a plugin, visit the link bellow