API testing using post man

I am new to api testing from postman.I went through several blogs and articles on api testing.But I don't know how deeper we can done testing. Also how can we write test for post request.I have the below department mode class from my web api.

    [Key]
    public int DepartmentId { get; set; }

    [Required]
    [Display(Name ="Department Name")]
    public string DepartmentName { get; set; }

    public string Description { get; set; }

    public bool IsActive { get; set; }

What all things to be tested while invoking a post request and get request against department controller for the above model.