how can I use this platform at work in a group of colleagues

[Penine_Uwimbabazi]

how to use a group discussion with colleagues 

[Kurt Klinner]

@Penine_Uwimbabazi 

Hi Penine 

welcome to the Atlassian community.

You picked Crowd as a product but that one is related to centralized identity management. If you look into collaboration between users you should check out confluence 

There is a good write up available at https://www.atlassian.com/collaboration/confluence-discuss-work-with-your-team that shows the different options

Hope that helps

Cheers

Kurt