Meaning of trad and pinyin

I am not able to understand what is trad and pinyin
Also i am not able to see chinese letters on my PC.
Is there any special software require to see chinese lettrs on PC
Please help

Before starting to read a Chinese lesson here, you need to inform yourself somehow (books, internet) about the writing system (simplified and traditional characters (“Simp/Trad”) and about the romanization system (“Pinyin” and other).

Wikipedia is a good start to learn the basics:

If you don’t see Chinese characters you need to install East Asian language support.