How to lock forum for guests?

[Daxy94]

I want to guests must register to enter the forum??How??

[Luky]

You need to set the permissions for each forum from admin panel=>Forum=>Permissions=>Forum Permissions control click on a forum and then uncheck all options (View the forum, Read the topics) for Guest.

[travis_cooper]

You mean you don't want specific, or maybe even all, of the topics viewable to guests? You can do this on a forum by forum basis using the permissions. Goto admin panel->forum->categories and forums. Here you will see the structure of all your categories and forums. For each forum almost all the way to the right you will see an icon that looks like a X/checkmark, click on that to modify permissions. Find the column that says view and the row that says guests and uncheck the box. Now guests won't be able to see that particular forum. Do this for all the ones you want to hide. Also when you create new forum you can set the permissions at that time as well.

ETA: Through the permissions you can actually create a forum where guests can post replies to. This might be a suggestion, or help type forum where you want your guests to be able to ask questions before they sign up. Their posts will just show up as guest.