constructor inn vb.net

Question

hi.. i m new in vb.net

i want some info about constructors.

1. What is the need of constructor and destructor?

2. In vb.net is it necessary to define default/parameter less constructor in vb.net when we define any constructor with parameter?

because i create on constructor which takes parameter so at the time of creating the instance of class when i create instance without parameter then its showing error "Arguments not specified for "x"..

Thanks !