Auto populate event from lead info

Auto populate event from lead info

We are looking to populate the event fields with info from the Lead whenever we create a new event.  I understand a custom function is needed, but I haven't been able to figure it out.
Basically what we are looking to do is:

Title = Lead Name + City
Location = Street + City + State + Zip
Description = Phone

And then we would set the day and time and save it.

Can anyone help with this?  I've seen other topics that are similar but not quite what we want.  Any help would be appreciated.