Javascript cookie exist else Script

Hi all Experts

I am in a need of a simple javascript script that can verify
if a cokie exist
If it exist: (replace the below and show) You already upgraded.

If not exist:
I would like it to show: You account is not upgraded yet Please upgrade your account, click here to upgrade<br> <center><A href="url"><img src="picture"></center>

also need seperate script to set the cokie

Hope u understand what I want thank you