If you want multiple ones then used edit boxes instead of InputText
Give each textbox an id i.e.
textbox1 = CreateEditBox()
textbox2 = CreateEditBox()
textbox3 = CreateEditBox()
If you want to get text from either textbox once they've pressed a button/sprite like a submit button for example then use: GetEditBoxText i.e.
textbox1Value$ = GetEditBoxText(textbox1)
You can find out if a particular textbox has focus i.e. the user is typing something in it, or at least clicked in it with GetEditBoxHasFocus(textbox1)
Check out all of the commands here in the Edit Box section of the page:
https://www.appgamekit.com/documentation/Reference/Input.htm
I'm not a fan of them myself but that's what you want if you want more than one