How to store longitute & latitude as a geography in sql server 2014?

I'm a sql beginner that knows how to get my users location in longitude and latitute coordinates. My goal is eventually to be able to select all rows from myTable Where distance is less than 2km. However on my way towards this goal there is some things that confuses me so I'll try to list what I'm failing to understand.I'm a sql beginner that knows how to get my use