Here you will learn about the different components on the Arduino board and then you will install IDE software and learn the program structure. 

First Step: get familiar with Arduino UNO Board. Have a look at this tutorial.

Second Step: set up and start experiencing IDE software. Visit website here

Third Step: learn the Program Structure here.

Fourth Step: learn the data types that you will use during Arduino programming here. You will find the following pieces of information:

You can also use a very useful Language Reference on website.