Locking threads?

Can users lock threads? I want to lock my thread so that people will respond to the one in the Project Requests area, but I can't figure out how to do it. I know we used to be able to. Am I just blind? or is there no way to do it? If there isn't, acn you lock my thread John? The thread is;
http://161.58.186.97/showthread.php?s=&threadid=83090

Thanx
Joey

I don't know if this is right, 'cause I've never used it, but...
I think that if you edit the first post in the thread, you have the option to lock the thread. Don't quote me on that though...:)