How do you reset password for mail in iCloud??

Your password for iCloud email is the same as for the whole of iCloud. You change it at http://appleid.apple.com - once you have done this you have to go to System Preferences (or Settings)>iCloud and click the 'Sign out' button (on an iOS device it's 'Delete account' - this does not delete the account from the server).

You then sign back in again using the new password. Your iCloud data will disappear from your Mac/device when you sign out but will reappear when you sign back in.

You signature says you are using 10.6.7 - I assume this is incorrect as this is not compatible with iCloud: if so could you please amend it to prevent confusion.

You can set it in your Profile - 'My Products' - where there is a drop-down menu covering all systems.

It sounds as if this has got to the point where you need Support to sort it out. If you currently happen to have AppleCare, either because you recently bought Apple hardware or have paid to extend the inititial period, you can contact them here:

http://www.apple.com/support/icloud/contact/

You will need the serial number of the covered hardware.

If you are not covered by AppleCare, then - in common with other free email services - there is no free support and you may be asked to pay a fee - as it looks to be their fault you may be able to argue that you shouldn't be charged.