How to backup using time machine?
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Take a look at this article from Apple Support → [How to use Time Machine to backup and restore your Mac](https://support.apple.com/en-us/HT201250)

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> Also, should the first backup be kept separate, in case you need to restore to the original condition of your system, and then do another backup which is then used to do hourly/daily backups/whenever backups upon? 

Well the more backups the better, but this is a bit unnecessary. You can always restore the original factory system by reformatting and reinstalling macOS. 

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Since you are new to Mac, assuming that you are coming from Windows, take a look at this article it will really help with the transition. 

[Mac tips for Windows switchers](https://support.apple.com/en-us/HT204216)