Q: I have iCloud on my iPhone but not on my MacBook Pro which only shows MobleMe.  How do I install iCloud?

Your signature says you have 10.6.8: this is not compatible with iCloud and the Preference Pane for iCloud does not appear. the minimum requirement is Lion 10.7.2.

You can access email on an existing iCloud account by setting Mail up manually:

Entering iCloud email settings manually in Snow Leopard or Leopard

You may be able to sync your calendars to iCloud by means of an unsupported hack, and there is a convoluted hack which has been reported as working for Address Book (and as not working by others - I've not tried it), but iCloud's other facilities will not work. This page outlines the situation with Snow Leopard and iCloud, including a link to the calendar hack:

http://www.wilmut.webspace.virginmedia.com/notes/icloudSL.html

Although it's not a cheap solution, Soho Organizer can sync Calendars and Contacts with iCloud on Leopard, Snow Leopard and Lion. A single user licence (multiple machines allowed) is $99.99.(I have no connection with this firm.)

For full access to iCloud's facilities you will need (if possible) to upgrade your Mac.

I  found these two webpages on how to sync iCal calendars and contacts with SL.  Use at your own risk:

sayzlim.net: Sync iCloud Contacts and Calendar on Snow Leopard

ICloud calendar/contacts sync with non...: Apple Support Communities

OT