Instructions
Open a text editing program and create a new text file with the same name as your map.
Open your "Counter-Strike Source" directory and place the new text file in the "Maps" folder.
Open the text file and type in the information about your map. Include instructions, player information or acknowledgments.
Save and close the file. Load "Counter-Strike Source" and start a new game using your map to play on. When the game loads, your text will appear at the start of the match.