Start of by learning C# first - ignore Unity until you have the basics done and properly sorted in your head. A course is the best idea - check locally, you may find evening classes - or a book if that isn't available (Wrox, Addison Wesley, and Microsoft press do good ones, or there is
Pro C# 7 - With .NET and .NET Core | Andrew Troelsen | Apress[
^] which I started with: a much earlier version though!). If you do go for a book, then start at the beginning and work to the end, doing all the exercises, even the boring bits: it's there so you know what is available and hopefully remember it's existence (if not how to use it) when you actually need it!
When you have some solid C# under your belt, then consider Unity - but don't try to learn both at the same time or you will miss far, far too much that could make your job a lot easier.