Could not load library client in my Source Mod.

I hope this is the right category... The first thing I want you to know is, I'm 13, I know litte about what I'm doing, and I am experimenting with Source SDK. I took the raw skeleton of HL2, and I set it multiplayer. I ran it and it says "Could not load library client." I know what this is. There are missing .dll files but I don't know what to do. Should I steal the server files from HL2 Deathmatch? What do I do to fix this? Please be specific...