How can I restrict a MySQL user to a particular tables

Assuming the user has no current privileges, you can do the following

GRANT SELECT, INSERT, DELETE ON db_Payroll.tb_Users TO RestrictedUser@'%'
GRANT SELECT, INSERT, DELETE ON db_Payroll.tb_Employees TO RestrictedUser@'%'

Depending on exactly which privileges you wish to grant the user, you can change SELECT, INSERT, DELETE to something else, e.g. ALL PRIVILEGES.

Afterwards, remember to flush the privileges so they become effective by running

FLUSH PRIVILEGES;

You can grant access to individual tables by running:

GRANT ALL ON db_Payroll.tb_Users to RestrictedUser@RestrictedHostName;

And similarly for other tables. Use a list of operations instead of ALL if appropriate.

You cannot grant access to individual tables which do not exist yet without granting access to all tables.