Please help in SQL code and Thank you

Please help to point out the error(s) in the SQL code:

select
c.cust_nam,
count s.qty_sold
from
customers c and
sales s
where
c.cust_id = s.cust_id,
s.sale_dat >= ‘20100101’,
s.sale_dat <= ‘20101231’
group by
c.cust_nam