How to add a user group to a user?

Hello Si Team

Honestly I do not really understand my own question.
Here is what I posted in the Hika Forum and here is the reply...
Maybe you want to skip to the end and see the Reply from Nicloas from Hika Shop....

Hika Forum my question:

Hello Hika Shop

This is I guess a kind of pre sales question.
As of now I have a workflow where I
a) Use Hikashop as a store front to display products in conjunction with Easy Social.
www.finalbug.net/paul-david-murray/233-course-list
b) Have a plugin that takes a customer from the product to a reseller.
github.com/DeligenceTechnologies/DT-Fast...Payment-for-HikaShop
c) Confirms that the product has been paid for at the resellers end in the Hika Shop Component.

The product I am selling is access to a password protected (Easy Social / NOT Joomla) group such as this here:

www.finalbug.net/groups-learn-post-produ...x-foundations-videos

One of the functions of the reseller is to send a email where I can insert a password from a list of e.g. 100 pre defined passwords.
I can generate passwords here for e.g.:
www.random.org/

I can then insert the passwords in my site using this component here:
www.jlexart.com/jlex-block

I am wondering if there is maybe a more elegant way of doing this with for e.g.:

www.hikashop.com/extensions/hikaserial.html

If so could you kindly point me in the right direction.

thanks

Paul

Hika Forum anser from Nicolas:

Hi,

HikaSerial can indeed add a serial automatically to the email/order upon confirmation of the payment. And that serial can be used with the "consume" page of HikaSerial to add a user group to the user and grant him access to some place of your website restricted to that user group. Now the user group consume plugin of HikaSerial which does that adds standard Joomla user groups.
If you wanted instead for HikaSerial to add a Easysocial user group to the user upon serial consumption, it would require the development of a small consume plugin to do that:
www.hikashop.com/support/documentation/1...html#consumer_plugin
It's not necessarily complex to do. If you're a developer and EasySocial can tell you how to add an EasySocial user group to a user, it should be a walk in the park.

The last sentence is the important one:

If you're a developer and EasySocial can tell you how to add an EasySocial user group to a user, it should be a walk in the park.

What does a developer need to know from a Stackideas perspective to get this to work?

thanks

Paul