I want to a e-cards or something like that. The user can choose the e-cards, after chosen, he must enter the some fields like name(to and from), email(to and from), message and
This is for *nix. Let's say you have a php script that sends email on a specific day called mailer.php
We are going to assume that you already have cron daemon running in the background.
If you have root access to your machine, then setting up a cron job is simple as editing a file.
Open up /etc/crontab file and add the following task:
1 14 * * * root php /path/to/your/scrip/mailer.php
This means, as a root, the mailer.php script will be running daily at 02:01PM. You can change the numbers to whatever you desire.