How can I add a link on the Tax Withholding page in ESS

Summary

How can I add a link and instructions on the Tax Withholding page in ESS- ideally if we could do this by state.

Content

Hi All-

We have a requirement to add a link to a tax form to help the employees in filling out their state and local taxes.  They would like a link added with some descriptive text.  If would be ideal if we could also control this by the state that is appearing on the tax form.  

Please give me some suggestions with some documentation as to how we can modify our Self-Service pages.

Thank you!