On the maps page 43 out of 59 maps have at least one error.
The errors range from small errors such as 'extra (unnecessary) files' or 'no arena or levelshot files' to larger errors mainly including the 'map or bak' files with the pk3.
Quick tutorials on pk3 creation
Create a folder on you desktop (or other)called "PK3 Creation" for the pk3 folders to be placed.
This is the list of folders that at least should be included...
/maps/mp/ {- This folder should contain BSP and GSC files (A bsp file is your compiled map and your GSC files are scripting for your map)
/mp/ {- This folder should contain your ARENA file (An arena file is used to add the map to the 'Start New Server' menu in CoD)
/levelshots/ {- This folder should contain a DDS levelshot (a levelshot is also known as loading screen. This folder and file is not a must)
Other folders that can be included in your pk3 include...
/sound/ {- This folder should contain any sounds that will be used in your map
/soundaliases {- this folder conatins the CSV files that load the sounds for your map
/textures/<textures>/ {- This folder contains custom textures (DDS format), <textures> to be replaced by the folder name you've used
*Do not include your MAP or BAK files in your pk3 as they can be used to alter you map*
Also, do not include any files that are created during the compile process (obviously except BSP). This includes LIN, POLY and PRT.
Once you have everything in the correct folder, you have a choice of 3 programs to use for creating the pk3.
WinZip, WinRaR or PakScape all which are free (either as freeware or shareware/trialware).
Pakscape instructions
Open PakScape and select File then New (CTRL+N)
Drag and Drop all folders in to the blank window.
Then select File then Save As. Add you map name and change filetype to pk3.
Pakscape is a freeware utility for creatin PAK and PK3 files and can be found on ModsOnline... HERE only 100kb and no installer.
Done

Edit: Removed WinRaR and winzip nistructions as problems arise from using it. Use Pakscape, its easier and successful.