how do i install the reminders app

you don't. It's part of the iOS

where/how do you find the reminders on the iphone4 - they only appear on my phone when an alert takes place from the reminders on my mac - when i click out of the reminders on the iphone, i can't get to the reminders until another alert is triggered. When i click on the ical icon on the main screen only the calendar appears with list, day and month options - no reminders are visible????...is something not dlownloaded correctly??...HELP

Reminder is a new app that comes with IOS 5.

If you have the latest IOS:

Settings > General > Reset > Reset Home Screen Layout

it still didnt create the reminders list on my i phone4 - the only time the reminders list appears on my phone is when an alert has been triggered - otherwise the calendar icon only shows the list, day and month - no reminder option at all...however like i said when an alert is triggered...it appears on the phone exactly how i would expect it

Calendar and Reminder are two different apps.

Reminders. The best way
to do to-dos.

Make all kinds of to-do lists for anything you can think of. Then add deadlines and locations. Even set alerts. Or just tell Siri, “Remind me to take out the trash” or “Remind me to pay my phone bill Thursday.” And suddenly, everything you have to do seems a lot more doable.
Learn more about Reminders