VS 2010 Textbox problem noob plz help

hello everybody
i know this maybe a simple problem for you all so please help me

i can use only one label i don't want to use more
i have textbox and a label and button
label1
textbox1
button1

everytime i press the button label1.text changes to what ever i choose it to
i want every time label1 = to text i want it to be copyed in the text box so far i can do that
but the problem is when ever textbox1.text = label1.text i can get only the first text
what i mean is that i want all text i have in label1 to be copyed under each other one after the other whenever i press button1 to change label text
eg
when i press button 1
label1.text = "hello"
if i press it again
label1.text will change to "how r u ?"
if again
label1.text = "good"

and so on

in text box i need it to be like this

at the first click
inside textbox :
hello

second click
inside textbox:
hello
how r u ?

third click
hello
how r u ?
good

under each other not next to each others

thank you

please help