When employers screen applications, they are trying to find an employee who will bring value to the company and will fit into the company culture. Your cover letter is an opportunity to demonstrate both things.
To do that in your letter:
Indicate that you understand the needs of the company and provide one or two examples of when you met a similar need at a previous job.
Be enthusiastic about the thought of bringing your skills to the company.
Each job application requires a different cover letter. You can get assistance from Client Enrichment Services. Ask your case manager for a referral.