Your resignation letter should be courteous and professional.
Give a specific date for your last day of work so your employer has time to plan for your departure and find a replacement.
Doing so can help you maintain a positive relationship with your former employer, which is beneficial if you need to use them as a reference.
Offering to train or provide training materials for your replacement will help make the transition period easier for everyone involved.
Even if you are not happy with your current situation, remember to be grateful for your opportunities. Thank your employer for their time, and wish them continued success in the future.
Include a way they can contact you, such as your email address or phone number if they need to reach you about any outstanding items.