I'm scared because price Bitcoin down, I do not know what to do with Bitcoin at this time

Why scared? Remember that before the surge we are sitting around $700-$800 as far as my memory is concern. Instead, take this as an opportunity to make another rounds of buying, yes embrace the dip as it was normal.
Advice? If you think you missed the train of selling price then just hold since it's just the same risk. While at the same time just continue with your method to earn bitcoin. Accumulate more and more. If you don't need to use your bitcoin then just let it sleep.
No one knows what will happen in bitcoin price so better play with it.
Good advice

Don't panic selling and take it easy.
Bitcoin can't go down so badly, the truth will come to the surface, just wait.
Don't we know the advantages of bitcoin? The price keep increasing as time goes on.
Sell rules : only sell if you don't have any option to get money. If you have, than let it remain save in your wallet.
Confess : have you panic sell too? Or you see it as the chance to buy within the dip? Because the price already recover.