Reg query in windows xp

I am looking for information about Reg query, i know all the software and hardware installed on windows xp system are edited by REG query but need more information about how it works and procedure to access it.

REG query allows you change, add or delete value related with registry.You can Read, Set or Delete registry keys and values, save and restore from a .REG file. For example : REG QUERY HKLM\Software\Microsoft\ResKit\Setup\InstallDir Displays the value of the InstallDir registry entry.

Reg Adds, changes, and displays registry subkey information and values in registry entries. To view the command syntax, click a command : reg add
Adds a new subkey or entry to the registry.

Syntax :
reg add KeyName [/v EntryName|/ve] [/t DataType] [/s separator] [/d value] [/f]

Examples

The following examples show how you can use the reg add command:
reg add \hklm\software\myco /v data /t reg_binary /d fe340ead
reg add "hkcu\software\microsoft\winmine" /v Name3 /t reg_sz /d Anonymous
reg add "hkcu\software\microsoft\winmine" /v Time3 /t reg_dword /d 5

Reg query : Returns a list of the next tier of subkeys and entries that are located under a specified subkey in the registry. Syntax : reg query <KeyName> [{/v <ValueName> | /ve}] [/s] [/se <Separator>] [/f <Data>] [{/k | /d}] [/c] [/e] [/t <Type>] [/z]