sqlite.net and multiple primary keys

I don't know what to do with my multiple foreign keys in sql.net.

I tried to use index but i don't realy know what to do.. Does someone have a solution or a tip ?

these are my classes :

 public class inscription
{

    [PrimaryKey, AutoIncrement]
    public int ID { get; set; }    

    [Indexed(Name = "ListingID", Order = 3, Unique = true)]
    public DateTime DATEHOUR { get; set; }    
    [Indexed(Name = "ListingID", Order = 2, Unique = true), MaxLength(19)]
    public string CAND_ID { get; set; }    
    [Indexed(Name = "ListingID", Order = 1, Unique = true)]
    public int CENTER_ID { get; set; }    

    [MaxLength(4)]
    public string CATEGORY { get; set; }    

    [MaxLength(1)]
    public string RULE { get; set; }    

    [MaxLength(11)]
    public string CDRIN_AGREMENT { get; set; }    




public class session
{

    [PrimaryKey, AutoIncrement]
    public int CDRSE_ID { get; set; }  

    [Indexed(Name = "ListingID", Order = 2, Unique = true)]
    public DateTime DATEHOUR { get; set; }  
    [Indexed(Name = "ListingID", Order = 1, Unique = true)]
    public int CENTER_ID { get; set; }  

    [MaxLength(50)]
    public string EXAM_ID { get; set; }  

}