Information on Setting up my own server for dod or css

Hi guys, was just wondering how hard it would be to set up a public server on steam for dod and/or cs:s i kind of need as much info as possible to help me do this. i.e. do i need a seperate pc to act as the server and if so what kind of spec would i need or how do i get server space in order to be able to do this, Basicly any information you guys could give me on this would be much appreciated and very useful, i'll say in advance thankyou guys