I'll try to answer your rather broad questions as best as I can...
1)what is the default namespace?
Are you fetching for something like c++ Std namespace? Well, there are no
such thing in .NET.
2?)what is the difference between a property and field?
A property is a field-accessor, i.e. they let you specify getters and
setters for the property. Also, when creating custom components, they can be
used in the property editor in design mode.
3) what is the difference betwen creating an object on stack and heap in
..net?
Hehe, well the first creates an object allocated on the stack and the other
on the heap. Sorry, couldn't resist. =) Actually, this is a huge and
important topic. You should read more about it on your own. A good
introduction is to look at classes and structs and understand
boxing/unboxing.
4) what is the diferecne betweeen close and dispose methods?
Hmm, read about the IDispose interface and the dispose-pattern and you get
the hang on it.
happy coding
- Michael S