I have 2 entities, one users and one messages. I want to create an method to be able to create a message but assign it to current user that creates it.

public class AppUser
    {
        public int Id { get; set; }
        public string UserName { get; set; }
        public byte[] PasswordHash { get; set; }
        public byte[] PasswordSalt { get; set; }
        public DateTime Created { get; set; } = DateTime.Now;
        public string Gender { get; set; }
        public ICollection<Message> Messages { get; set; }
    }

[Table("Messages")]
    public class Message
    {
        public int Id { get; set; }
        public string Title { get; set; }
        public string MessageBody { get; set; }
        public DateTime CreateDate { get; set; } = DateTime.Now;
        public int AppUserId { get; set; }
    }

I need an httpPost for a user to create a message so when i output user details, it shows also messages created by him