He lacks little!!! (irritating problem)

Hi Friends, do I need a small help, when do I put mine Cd-Key of Half-Life in Steam he carries a little but later it does reject him/it, what do I make? is it necessary to have Half-Life? What version of Half-Life? And if he/she needs of same Half-Life, later the one what I make?

If somebody to pass a simplified tutorial it would be very thankful,
Thank you very much,
DJS.

Email [email protected] for help on getting your cd key working.