Get your Free Autodesk software from Autodesk - It is Free and you get 3 year license.

Autodesk - 3 year license Free for Student & Educator

If you still does not have Autodesk Software, you should get one through Autodesk. 

If you are student or educator, Autodesk give you 3 year license on their Autodesk Software. 

AutoCAD 2016 Tutorial - Drawing Unit settings in AutoCAD

AutoCAD 2016 Tutorial 

How to change Unit settings in AutoCAD 2016

You can change the Units in AutoCAD. In the US, we normally use inches and feet but sometimes we have to work with centimeters and meters for international projects. I am going to show you how to change your units in AutoCAD and it's short-cut. 

Short-cut to open up the units preference box 

(Drawing Units box)

Type: u + n + enter (do not type +) 

Once you type u + n + enter, the Drawing Units box will be appear as shown (IMG 1).

IMG 1 (drawing units in AutoCAD)

In this unit settings, you can change your AutoCAD units into an Architectural (foot and inch system), Decimal (metric), Engineering (feet and inches but decimal), Fractional (inches only - cabinet makers), or Scientific.

For Architectural units, ( ' ) indicates foot and ( " ) indicates inches. You don't have to put ( ' ) or ( " ) in AutoCAD. The AutoCAD automatically indicate as inches when you put your numbers. For example, if you type in 14, the AutoCAD will indicate that number as 14 inches.