Hi Beesflirtn ! 
Welcome to the forum !
Old Hag is a recurring question amongst beginners. You have a search engine on this forum (in the top bar) and you can search for “old” and “hag”, and find all these topics :
Old Hag Syndrome
The Old Hag
Old Hag?
The Old Hag syndrome!!
It’s better to post in an existing topic, because answers won’t be scattered through the forum. 
About your question : you don’t have to be afraid of Old Hag. It’s not a dream character that you’ll often meet. Most likely, you won’t meet her at all !
In fact, Old Hag is related with a sleep disorder called Sleep Paralysis. For people experiencing such a disorder, the mind wakes up before the body, and they find themselves paralyzed during a few seconds (up to 2 or 3 minutes).
In some cases, Sleep Paralysis is accompanied with hallucinations. As sleep paralyzed people are already afraid of what happens, these hallucinations are often frightening (ET’s, demons, Old Hag, etc.)
Concerning LD, there is a confusion, because when you practise WILD (and only this induction technique), you try to volontarily reach a paralyzed state, which many LD’ers also call SP. But these hallucinations don’t appear in this state. They are only related with the SP disorder.
I hope you won’t be afraid, now ! Remember that all you can experience in LD… is just a dream ! 
mods : wouldn’t be a great idea to gather all the posts about Old Hag in a “BIG Old Hag topic ?”