How do you search for a thread in 4chan?

I just cannot figure out how to search through the threads for a specific keyword, is that possible in 4chan? TIA

I how do I find a post from today or yesterday,
I have been getting harassing phone calls out of the blue,
then I got a call from someone in Alaska telling me
that my cell phone number was on the 4chan site,
requesting people to call my cell phone and harass my
high school son...

Who do I contact for access to postes in hopes of
finding out who did this...If it is true?

thanks