First you fill out the covenant form and sign and witness it.
Then you give the money to your mother each year (ideally by cheque so that you can prove you did) but deduct 20% from the amount that the covenant says you should give her.
Then fill out a from 12 and send a copy of all the documents with it to your tax office at the end of the tax year.
Your mother will have to submit a form 54 also, again with copies of all the covenant documents.
You will both get a tax refund about 8 weeks later.
I send in a photocopy of the cheque and my bank statement showing that the cheque had been cashed. I am about 4 years into my covenant now and I can't remember why I do this. I think that Revenue asked me for it in year one.