applescript?

set thetext to "Hi, would you like to surf the net?"
display dialog thetext buttons {"NO!", "Indeed I would"}

if the button returned of the result is "NO!" then
set thetext to "Ok, so you won't surf the net. Do you want to write?"
display dialog thetext buttons {"i kan't spel", "Yes"}
end if

if the button returned of the result is "Indeed I would" then
tell application "Safari" to activate
end if

How do I get it so the last bit responds to the first bit instead of the second bit? Please help me!