Ask a landlord-tenant lawyer and get answers ASAP
Your letter should look something like this:
Dear Mrs. Tenant,
You are hereby given an eviction notice and notice to vacate the premises on or before DATE, the premise owned by YOUR NAME in the city of XXX, California.
The reason for this eviction notice is:
(X) Your failure to pay rent due in arrears. A demand for payment was made on DATE, and you have refused to forward the necessary funds to pay for the rent during this period.
You are hereby notified that if you make all outstanding payments before the date of eviction, you will be able to remain in the premises as long as you continue to pay your rent.
Here is more detailed letter:
Either one of them will work, it just depends on the style you want to go for.