Writing a CV can be a daunting part of any job application, but it is also one of the most important parts of it. Writing a great CV is essential, and what you want to focus on to do this is making it concise and to the point; 1 or 2 pages long is typically the right length, but it can be longer for more technical and skilled professions.
A very important part of any CV is your employment history. It can be difficult deciding what to include and what not to and how much detail to go into, but generally speaking you want to include all of the jobs you’ve had, but only go into greater detail for the jobs which were more important and/or relevant to the one you’re currently applying to. It is very important that you include all of the jobs you’ve had and the duration of the employment, as any gap in employment is going to be a bit of a red flag for any prospective employer.