How would i write an SQL query to use Join to display CustLastName, CustFirstName and corresponding Cust_order number?

Experts,

I am trying out SQL queries and wondering how to use the join between two tables (Customers and Orders) to display last name, first name and corresponding Cust_orderNo for all records.

Table_a    Customers                                            Table_b   Orders
C_ID      CustLastName   CustFirstName           Order_ID     Cust_orderNo   C_ID
1            Ant                      Adam                           1                  123                     1
2            Bear                    Brent                            2                  456                    6
3            Cat                      Cathy                            3                  789                    6


Here is what I have:
Select Customers.CustLastName, Customers.CustFirstName
FROM Customers a JOIN Orders Cust_orderNo

Also, if there were thousands of records, what is the most efficient syntax to use for this problem?

Thanks!