Writting a professional cover letter is not for the individual .It requires an expert to write a good cover letter that covers all the aspects of your jobs. But ,if you can afford it .Then you can write it yourself by following some tips . firstly,say who you are and why you want the job,Secondly , Talk about what you're good at and how it can help the company. , Thirdly,Show that you're excited about the job and the company.Lastly ,Keep it short and say thank you in the end.