For calendar, check date() in manual. There is nice example with mktime() there.
Events can be added to database, with one field being date and the other description. If one day can have only one event, date will be key. If not, you can have autoincrement key (usually named id).
Password? The easiest way is to hardcode it to php script. If you need more of a security, save md5() hash of each password to database and check that.