Sorry, I couldn't understand what you exactly mean by "I want a friend of mine to be allowed to update certain files". Do you want to allow your friend to update file of your webserver directory or you want to allow him your system access for a particular folder.
You can have a look at vsftpd (a FTP server). You need to install and configure it.
Regarding, your question about HTTPS, you need to modify your apache configuration to listen on SSL port. For apache configuration help, you can look at Apache Reference