2nd Step-WHAT MUST I HAVE TO DESIGN..?

Alright. Actually for designer,they design by pc program to make they model for real.
Ok,this part has a separate to a 2 part. That a:
1. 2d dimensi drawing
2. 3d dimensi drawing

What that...?
That very difficult to explain to you,but after this you wiil know what that a detail
however i will give a you list of software for a design

-Autodesk Autocad
-Autodesk Inventor
-Solidwork
-Catia
-CADCAM
-anymore...

All this software are use for the product design.

TOOO MUCH.....?
yup. Too much. Because this sector very big. And also different depends our country. For example in Malaysia almost use Autocad for 2d drawing and Solidworks for 3d drawing.

Below are example for 2d drawing and 3d drawing This example for 2d drawing

This example for 3d drawing