getting dnn user information from dotnetnuke module is
easy.

you can get dotnetnuke user's User Credentials
and Profile data by the following way -

exporting to data in excel is a very common practice
in business website.one can use asp.net Response methods
to export to excel which is easy to do using a gridview.but
contents not appear properly like there will be white back-
ground over excel rows and this way is not efficient too.

you can create custom navigate url in dotnetnuke to send the url or
use it as a querystring in another page by the following way -

If you used itemtemplate for items in datalist control then
you can easily delete,edit and then update items
using edititemtemplate.to do that add a itemtemplate and
edititemtemplate in the datalist.also you have to add
command buttons and command event handlers -

following are some practice problems for c#.net
programmers.teachers try it in classes.students
or novice c# programmers solve those problems to
practice c# programming in -

Its easy to implement OnCheckedChanged event of RadioButton
control but most programmers makes mistake by not
including AutoPostBack="True" property in radiobutton
control.sometimes OnCheckedChanged not works for that
reason.here are the full working codes -

you may need to register javascript file/css file from code
behind when needed.for this follow the codes below -