If you are looking to do a placement in a job maybe to gain some more experience whilst studying then you need to target companies that have taken on placement students in the past and that are right for what you are studying and your skills.
Look at what you are hoping to do when your studies are finished and concentrate on those skills so that hopefully you will choose a company that may lead to a job after you have finished your studies.
If you are looking at how to write a covering letter to support your CV, please see the below example.
Related: Graduate Cover Letter
Job Placement Cover Letter Example
222 Every Road, Any Town, AA1 1BB
Mrs Jane Smith
Application for a placement role
I have recently seen that you take on placement students whilst they are studying and I would be very keen to join you and put my studies into practice.
I have been studying nursery nursing (or whatever you are studying) since (when, how far through are you, how long do you have to go etc) and now I am keen to start learning and working in real life situations as I feel this is the only true way to learn well once you understand the basics.
I have always wanted to work with young children and I am very enthusiastic. I am a very positive person, I have a great deal of patience and I feel that the rewards of developing young children in a nursery setting and preparing them for school is very important.
Throughout my studies I have also been learning about how to work with others in group situations as well as on my own initiative and I feel that I am very motivated and I a keen to learn.
I am required to go to college for my studies on a Thursday each week but I am available for a placement role on all other days if this would fit with your requirements.
I have enclosed my CV for your consideration and I would welcome the opportunity to discuss this further with you.
Thank you for taking the time to read my letter and CV.