Auto Populate Meeting from Lead

Auto Populate Meeting from Lead

I am looking to populate the meeting fields with info from the Lead whenever we create a new meeting.  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 = 'In Home Appointment" + Lead Name + City
Location = Street + City + State + Zip
Description = "Description of meeting- about a paragraph long"

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.