Put the "ESF-Bot.dll" in your "esf\dlls" directory, then change the "liblist.gam" file (in notepad) in the "esf" directory so it says:
gamedll "dlls\ESF-Bot.dll"
instead of
gamedll "dlls\hl.dll"
Run the game with console (example: "C:\Games\Half-Life\hl.exe -console -game esf"), and in the game type "addbot" in the console (open console with '~'-key) to add a new bot to the game.
You can use "kick [Bot Name]" no brackets just the bot name case sensitive, to kick a bot.
NOTE: It is very important that the name of your ESF directory is "esf"! Otherwise the game will crash at startup!
Have fun!
(the readme file so you can see wath you should do)LOL