Hi,Can you suggest me which topics i need to cover to clear my basic concepts in c# and asp.net?

Be very strong in OOPS first, those are must.

Then start Delveloping Some Logical coding using basic C#, which will use just For loop, while loop and if else.
Example, Generating tree
1
12
123
1234
try some more stuffs like this,
Try Matrix multiplication


Once you done with OOPS and Logic

Start with C#
Try to understand what all datatypes are there in C#
Try to understand Proeprties vs Variables
Understand arrays and Collections
Try some generics
Try some delegates

Asp.net
Most important ASp.net Page life cycle
look after some HTML and web server controls
go for validation controls
Try ro create and Complete Database driven application, like Gridview with a form,New,Save,Update and All
Learn AJax and try to implement updatepanel in above example.


Hope this helped, Check this is correct answer if it helped.