How to add user data in Sugar CRM custom module and make relationship in PHP?

Step 1: Please follow the same steps as shown in this article... How to use Sugar CRM API integration with PHP?

Step 2: But please note the following points for custom module.

Note 1: Custom module name must be like 'CustomModulePackagekey_ModuleName'.
Note 2: 'link_field_name' must be the Related Module Name
These above details you can find in 'ModuleBuilder' section of Sugar Admin account.

Step 3: Done. :)