I like to know how can I back up my apple, Thank you

I have a Mac book Pro and I really love it how co I back it up? I have a an external hard drive but my paper wprk got lost and I don't know how to get in it I got it to back up my Apple but Iam at a lost now can you please help me? Thank you David. Please feel free to email me Again thank you for your time. You will realy make this dissable guy happy. 73 ( That means God Bless) Thank you

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