Start by reading the docs, start here.
Some tips
Although youtube and alike can be a great resource it is often out of date, therefore always start by reading the docs, then use the other resources to backup that info.
HA moves on fast with updates every month, which can and do include breaking changes which youtube will not keep up with.
You will come across many issues you cant find the answer for as you progress, we all did. Come here and ask a good question and you will get all the help you ever need, ask a poor question and you will just be asked to ask a good question.
see this
Do not be put off by the learning curve and start with the easy stuff, lights on at dusk and that sort of thing.
And finally always read the docs first. I can’t emphasize this enough.
We are all here to help, and will go out of way to help, but if you insist on following 2 year old videos you will end up in a mess.
Good luck with your trip down the rabbit hole 