LiveAgent helpdesk software allows you to include a forum category in your customer portal. It allows users to post new topics/questions and other users are able to respond to them. When a new topic/question is created it creates a ticket in your LiveAgent and your agents are able to answer it like any other types of tickets.

Creating a forum

Step 1: In the agent panel navigate to Customer portal --> Knowledgebase --> Create and choose "Forum" 
Step2: Now you may choose a category under which the Forum will be placed, enter a custom title of the forum, decide if it is an internal or public forum, add keywords for better SEO optimization, write a brief description and choose the department that will handle forum entries.
Step 3: If you want to add any topic or question into this forum category go to Customer portal --> Knowledgebase --> General (forum´s category) --> Troubleshooting of 500 Internal Error (forum´s title) --> Create (topic) ; Here you have to define the "Question" - which stands for a title of the topic you want to add now ; and "Add some details" - which stands for describing the topic
Interaction in the forum
Customers registered in your Customer portal can see suggested forums right in the main page. Once they open it, they have an option to "Ask new question" or participate in previous topics.
If there is a new question posted or any topic commented, it will appear among the tickets and your agents may reply to it easily from the agent panel. 
Customer´s view
Agent´s view