The process of applying for a job is not just about creating a resume, you also need a cover letter to support it. Your cover letter is the opportunity to go into a bit more detail about what you are currently doing and why you are looking for alternative employment. One A4 page with your key points will be sufficient for a cover letter. This is how to write a cover letter and give yourself the best chance of success.
You should find out who to address the cover letter to and quite often you will find these details in the job advert. If not, you can address it to Sir/Madam or to 'whom it may concern', but this is the last resort as you should really try and find out who to address the letter to. You can always send an email and ask if it is not clear in the advertisement. Cover letters are different to emails, so don't simply say 'hi' on it as it might not be appreciated by the employer.
The opening of the cover letter should address which job you are applying for and what you are currently doing. An example of this would be:
I would like to apply for the role of Administration Assistant. I am currently working in a temporary administration role but seeking a permanent role, and this looks ideal based on my skills and experience.
The cover letter is the chance to briefly
describe why you are suitable for the role. You can mention some of the skills of the role and how these relate to your own. If there are specific qualifications which are necessary and you have these, make sure you mention this too. If you are interested in a job, don't have the relevant qualifications but you are working your way towards them, don't let this put you off applying. For example:
I notice from your job advert that an HND in Administration is a requirement for the role. I do not currently possess this, however, I have just completed my HNC and will hope to have the HND in the next year.
You can talk a bit about your career goals in the cover letter, without going into too much detail. You may want to talk about the fact that you are looking to join an organization where you can develop your skills and grow within the business. Unless the role is temporary, most employers will want to hire someone who is interested in progressing within the business.
You should sign off the letter by saying that you look forward to hearing from them and then 'yours sincerely' with your name. You don't need to physically sign cover letters anymore, it is enough to just print your name.