how to add text or digit to listbox?

how to add text or digit to listbox?
follow this code

listbox1.items.add("your text")
or
ListBox1.Items.Add(TextBox1.Text)
for combobox is
ComboBox1.Items.Add(TextBox1.Text)

and here

how to remove text from listbox ?

ListBox1.Items.RemoveAt(listbox1.SelectedIndex)

ListBox1.Items.RemoveAt(0) it's remove index from 0