create wordpress site to take place of an existing non wordpress site

I am learning wordpress. (have been a long time WIX user). I have several friends that have existing websites that are hosted and created all over the place (i.e. go daddy, host gator, etc.) They would like me to create new sites for them using their existing domains. Some want to stay with their current host. Where could I find tutorials on how to create a new site on wordpress, then link their existing domain to it on their current host? I may be able to get some to change to hostinger, but not all. Any suggestions? Thanking you in advance,

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