Need help understanding what i am doing wrong in my insert statement

Question

insert into employees (employeeid, firstname, lastname, title) Values ('1001', 'jack', null, 'shepard', 'salesperson');
insert into employees (employeeid, firstname, lastname, title) Values ('1002', 'jack', null, 'shepard', 'salesperson');
insert into employees (employeeid, firstname, lastname, title) Values ('1003', 'jack', null, 'shepard', 'salesperson');
insert into employees (employeeid, firstname, lastname, title) Values ('1004', 'jack', null, 'shepard', 'salesperson');
insert into employees (employeeid, firstname, lastname, title) Values ('1005', 'jack', null, 'shepard', 'salesperson');
insert into employees (employeeid, firstname, lastname, title) Values ('1006', 'jack', null, 'shepard', 'salesperson');
i am getting this error message
Msg 110, Level 15, State 1, Line 3
There are fewer columns in the INSERT statement than values specified in the VALUES clause. The number of values in the VALUES clause must match the number of columns specified in the INSERT statement.
also 
insert into products (Name, price) values  ('shirts', 12.99);
insert into products (Name, price) values  ('shirts', 14.99);
insert into products (Name, price) values  ('shirts', 11.99);
insert into products (Name, price) values  ('shirts', 14.99);
insert into products (Name, price) values  ('shirts', 13.99);
insert into products (Name, price) values  ('shirts', 15.99);
insert into products (Name, price) values  ('shirts', 16.99);
Msg 515, Level 16, State 2, Line 2
Cannot insert the value NULL into column 'ProductID', table 'practice.dbo.products'; column does not allow nulls. INSERT fails.
The statement has been terminated.
what am i doing wrong?

Answer 1

insert into employees (employeeid, firstname, lastname, title) Values ('1001', 'jack', null, 'shepard', 'salesperson');
i am getting this error message
Msg 110, Level 15, State 1, Line 3
There are fewer columns in the INSERT statement than values specified in the VALUES clause. The number of values in the VALUES clause must match the number of columns specified in the INSERT statement.
also 
You have 4 columns in the insert( employeeid,fname,lname and title) however you are passing 5 values...
What does NULL represents? Is it middlename, then you need to add in the column list of  insert as well.
insert into products (Name, price) values  ('shirts', 12.99);
Msg 515, Level 16, State 2, Line 2
Cannot insert the value NULL into column 'ProductID', table 'practice.dbo.products'; column does not allow nulls. INSERT fails.
The statement has been terminated.
what am i doing wrong?
It looks like your table products has a column productid as not null. As long as you are not passing the product id in your insert statement, it will try to insert productid as null which will break. If productid is a increment values, then you need to use
either identity or sequence(if you version is 2012 and above).