This plugin enables Net-Results Marketing Automation across your entire WordPress blog/site in about 10 seconds.
It is an number that Net-Results assigns to you that uniquely identifies your account.
Yes, in the capture code that was emailed to you when the product was provisioned, you will find it starts something like this:
Where the number in data-pid is your PSID. Do not include the double quotes, and do not use XXXX - it must be a number.