Redirect in .htaccess



Please forgive me if my English is poor. Also please tell me if
this is wrong place to ask this question and tell me better place.

When searching web for information Re: .htaccess and redirecting,
I see many different examples of methods.

I wish to be able to say "this is good method that I can always use"
even if exists other good methods.

I wish not be confused by many different examples of methods.

I know is much to ask for to write example .htaccess for me but one
"known to be good" example with "#" comments saying what each part
does would be very large help for learning.

Examples I desire to see: In following examples I desire person
typing in URL OLD to see magic URL change in browser URL NEW.

I Also desire search engine following link to URL OLD to see
301 redirect permanent to URL NEW.

Examples desired to see:

OLD: http://www.example.com
NEW: http://www.example.com/

OLD: http://example.com
NEW: http://www.example.com/

OLD: http://www.example.com/directory1/
NEW: http://www.example.com/

OLD: http://www.example.com/directory2/
NEW: http://www.example.com/directory3/directory4/

OLD: http://www.example.net/
NEW: http://www.example.org/

Many thanks for future help. I have web searched and read
many documentations and I am still confused.

.

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