how can i download ichat on Yosemite?

Need more help... as a casual user of Skype (formerly) and Ichat (1 or 2 a year) I do not understand how messages replaces Ichat. The Imac I just acquired has the camera built in. I find no references to that in Yosemite. On my MacMini running an external apple camera, when it's turned on ichat automatically opens.  I've found nothing in Yosemite regarding the camera, etc. In Ichat on a Mac Mini running Tiger, using it was real easy... Examining 'messages' terminology has me in the dark as to what to do. Is there any kind of realistic guide>>>??  As automated Apple has made other aspects in Yosemite, I would hope that the process of viewing the persons on the other end is as easy. I can send email messages, so why would I need 'messages'....  HELP! this user is totally lost with messages...

HI,

AS you may remember iChat could use the AIM and Jabber services to Chat with Buddies of those types.

You may have also used it in Lion (OS X 10.7.x) where iChat 6 could also join the Yahoo service.

Your main interface was the Buddy List itself.

You highlighted a Buddy then either used the green icon for Video chats (or Audio if they only show a Mic) or the icons at the bottom.

In fact a double click on the line of a Buddy opened a Text Chat window.

On the iPhone in the iOS you have or had Messages which did the Apple Only Service of iMessages or SMS to non Apple phones (and in fact to iPhones not registered for iMessages)

In Mountain Lion the app was called Messages and adds the iMessages account to the app and changed the Main interface control to the new tabbed Chat window that can also start New Messages and select either Contacts (for iMessages) or Buddies.

The "Details" that replaces the blue + allows you to do Video, Audio  or Screen Sharing  when you are in conversation with Jabber or AIM Buddies  and will invoke FaceTime  to do Video chats with iMessages Contacts.

The iMessage account has no Buddy list.

It relies on the main window/Interface.

The Accounts pane looks similar to iChat (slightly different icons and slightly bigger)

Apple IDs issued by Apple (@Mac.com, @me.com (linked to iCloud) and @iCloud) still works as AIM screen Names like they always did in iChat.

AS you can See I have my original AIM (AOL) listed iconed Name as well as Yahoo and Google with their icons, plus some other accounts with the plain Blue and White Speech bubbles  (iCloud/Apple ID and an @Mac.com  plus a Non Google Jabber account on view).

Bonjour is still an option for LAN Based chats.

In broad terms Messages can be thought of as being able to join 5 services.

AIM,  (To AIM Buddies and part of iChat since day 1)

Jabber, (To Jabber Buddies including Google and Facebook Chat since iChat 3)

Bonjour. (Since iChat 1 Day 1 but called Rendezvous originally.  For LAN Based Chats)

Yahoo (as in iChat 6 onwards)

and the new iMessages (Apple Devices registered for iMessages be they iPads, iPhone or Macs (and some iPod Touch devices))

8:04 pm      Tuesday; November 18, 2014