Private topics can be visible to the users by their usergroup.

Hello i want to know, how i can set private topic, the default way to create topics in some spaces of my forum.

Because i want to have, a space where the users can create a topic but they only can see their own topics and don't see the topics of the other people. Like a ticket support system. 

Interesting but why would a user want a private topic only he/she can see? Or have I missed something?

Go to Dashboard > Forums > Settings > Forum Accesses Tab, For example Edit Standard access and enable/check "Can set own topic private" option.
Then go to Dashboard > Forums > Forums, edit the needed Forum/Category and in Forum Permissions field set for example Registered Usergroups Forum Access as Standard Access.

Now, all Users who have Registered Usergroup can set their topics private, and those topics can be seen by them and only by those Users who have the permission. As Default in wpForo those are Moderators and Admins.

Because i want to have, a space where the users can create a topic but they only can see their own topics and don't see the topics of the other people. Like a ticket support system.