Hello @vasil1682, the IPS Framework is great and provides the needed properties and methods for this.
If you want only a certain user group to see the content:
{{if \IPS\Member::loggedIn()->member_group_id === X}}
// This content is only visible for the specified userGroup,
// in this case it would not work since X is not a user group, replace it with a GroupId ;)
{{endif}}
If you want multiple user groups to see the content:
{{if \IPS\Member::loggedIn()->inGroup( array( 1, 2, 3 ) )}}
// This content is only visible for GroupId 1, 2 and 3
{{endif}}
I hope that I could help you, have a nice day and good luck with your forum.