Step 1:

Go to this folder "{Your vtiger root}/vtlib/ModuleDir/"  copy any of the folder you want to create module for which version if vtiger . Paste in to {Your vtiger root}/modules/{Your Module name}.

Step 2:

Go to following directory "{Your vtiger root}/modules/{Your Module name}/" . You have to change the files name as following. Replace "ModuleFile" into {Your Module name}

ModuleFileAjax.php         ->      {Your Module name}Ajax.php

ModuleFile.js                       ->      {Your Module name}.js

ModuleFile.php                    ->      {Your Module name}.php

Step 3:

edit the following file in your faverot  editor "{Your vtiger root}/modules/{Your Module name}/{Your Module name}.php"

change "payslip" into "{Your Module name}" case sensitive

Change "ModuleClass" into "{Your Module name}"