Our youth website redirects to porn sites

Currently when people google us and visit the link to our website it redirects them to porn. When someone manually enters our website in the address bar it does not seem to be an issue. Could someone please help me correct this? I am getting multiple calls from parents.

onenten.org

I have tried reading other posts with instructions on how to fix the issue however I am unable to comprehend the instructions. I am new to website management so I need things extremely simplified, step-by-step to understand how to correct the situation.

Thank you,
Crystal