No earnings, job for my wife. can we set up self employment to contribute for individual IRA? How much will be self employment tax for no earnings?

[DoninGA]

If you do not have any net income for the self-employment there will not be any Self-Employment taxes.

You cannot contribute to an IRA if you do not have any taxable compensation for the year.

[Carl]

I assume you're inquiring about a spousal IRA where you file a joint return, but only one of the tax filers works and has earned income. Start reading at https://www.investopedia.com/what-is-a-spousal-roth-ira-4770888