I'll try to translate:

ThisForm.TreeView1.ImageList = ThisForm.ImageList1.Object  ' Specify ImageList
ThisForm.TreeView1.Nodes.Item(3).Image = 1

You need to add Image List control into form. And icon may be specified while addind a node:
ThisForm.TreeView1.Nodes.Add(,, "Key", "Text", 1)

>Probably a question that has been asked before, so i'm going to ask it again:
>How do i add icons to a Treeview contol in VFP?
>
>I did find the following code in MSDN for VB but couldn't find any examples:
>
>>>>>>>>>>>>>>>
>TreeView1.ImageList = ImageList1 ' Specify ImageList
>' Use the value of the Index property of ImageList1.
>TreeView1.Nodes(3).Image = 1
>' Or use the value of the Key property.
>TreeView1.Nodes(3).Image = "image 1" ' Assuming Key is "image 1."
>>>>>>>>>>>>>>