Whilst some employers will be happy with just a CV most will want more, at least a covering letter (or email) to compliment your CV, or usually you will be required to complete an application form.
Any covering letters you draft to accompany your CV will need to be targeted specifically for each role. The same is true for any application forms that you complete.
You will need to research the employer and their requirements for that opportunity to make sure that you give good evidence of how you meet their criteria.
Don’t panic there’s lots of help with this available through the resources in MyCareer, which provide you with practical techniques aimed at helping you make your cover letter and application as powerful as possible.