How to use Parseval's relation?

Hey guys, I don't quite get how my lecturer got the following result:

How did he get X[0]=1? I am actually not sure how to compute |X(e^jw|^2, do the "|" symbol mean modulus?

Thanks!

-Question Attached.

Everything between the "| |" symbols indicate you use the absolute value.

duffy said:

Everything between the "| |" symbols indicate you use the absolute value.

Click to expand...

Ah okay, but I still don't get how to compute it though...