open v8.1 on an imac G5 from old G3

I have been using Freehand 8.1.0 on my old PowerMac G3.
I just got an iMac G5 which has Classic format on it. I installed the Freehand disc, transfered files but cannot open them.
Get message "cannot find default application"
Is it possible to open my years and years worth of work?
I cannot imagine having to recreate everything from scratch.
I am not a techie, so if someone is so kind to answer my question, please be gentle.
Thank you