using asp.net membership Probvider you can easily
make a user login using username and password and redirect to
default or any page by the following way -

there are many ways to do that.one of them is as
follows -

You need to check if the value of the checkbox is
set or not by isset function of php.

if you having a lot html strings,you may want to
have only plain text removing all html tags.you
can do it using REGEX

if you want to resize your asp.net textbox height according
to content then these codes will help you perfectly.

there are different kind of joins available by sql like
inner join,left join,etc.by the following example i will show
how to do left join which i used in my application to
get data from two tables -

you can put application specific settings in the
appSettings section of your app.config file in your
c# windows form application.you can access,edit,update
those settings.I show you how -