Hi Lewis1, if you are not already registered as an employer you need to complete a Form PREM Reg which is available from the Revenue website or if you would like to PM me your email address, I can send one on to you.
Once you are registered as an employer, your daughter can be registered as your employee.
You will then need to submit monthly or quarterly Forms P30 to the Revenue in order to declare and pay over the PAYE/PRSI/income levy on your daughter's salary. You may require some assistance in processing payroll if you have not done this before.