Hi,

Check out some of the multiplayer tutorials and you will find that it is possible to create something basic quickly.
However creating a large game will need some programming and design skills. It depends on your experience and talent if you can master this.
Server requirements will vary on game design, if you can design a dedicated server to handle things it would take much less than if the server would need to use the full game. Also it will depend on how much data there needs to be synced.

To be short, it is impossible to give an answer. If you make a game like Crysis, expect that you need a heavy server. Make multiplayer Pong, and you might use your home PC.