.......Here goes:
You need the retail version of Half-Life or Counter strike before being able to play. Install either and update them to the latest versions (google.com to find these updates). Then you install ESF beta 1.1 full version (which you downloaded I hope), and install it into your HL/CS directory. Then simply click on your desktop icon that is created along with the installation to play the game. In-game > Multiplayer > Quick Start, and you're set.
And before you ask, run the flash manual in your ESF directory to find out how to do stuff in the game.
And read the forum rules and stickies found in the top of various sections as well, it'll help you.