Ical Permission

I have a mac book pro - 2012 - most updated version of mac and cannot gain permission to view and write on my calendar? Last week I did, not sure what happened. I followed the suggestion - ical in finder - file - get info - changed permission to allow me to read/write but nothing has changed? No sure what wheel, everyone and system mean either? what should they say read - read/write - no access? Thank you for any assistance...