First, you need to download K9 webprotection.
Install it and use default settings, with two exceptions.
Activate the bark when you are on a forbidden site and make sure you internet access is completely locked for a day after you have tried to enter a blocked more then 5 times.
Use a really long and complicated password you won't remember and don't write it down.
Now your PCs should be save.
I got an iPhone, please make sure it's safe to use for a little kid like me
