Ok so if you have Windows 10 Professional you can use the Bitlocker by going to Security:Settings and choose Encryption
Here's a video link to help you:
Or if you have the Windows 10 Home you could upgrade it to Professional for $99.00
Or if you want to encrypt in DIY fashion try Veracrypt.
This article recommends 3 alternatives to the now defunct TrueCrypt but I think VeraCrypt is your best bet!
See this article:
Hope this Helps!