I want to get all login user list at welcome user page so how would i do that?

I want to get all login user list at welcome user page so how would i do
that?

I want to get all login user list at welcome user page .show each user can
see the login user list.For that I have created a session ["username"] in
login page and after that i want to use that sesion in session start
method of asax and i want to retrieve all the login users and store it
into application scope and i also want to remove and insert users on login
and logout page.so i am not getting a way how would i do that .because i
am new to the concept called global asax file thanks