Two options,
1. Create a combo to select name from, when the RowSource of the combo
includes both fields Name And Address
On the Control Source of the Address text box you can write
=[ComboName].Column(1)
Note: the column number start with 0
2. Use DlookUp On the After Update event of the name text box
If Len(Me.[NameTextBox] & "") > 0 Then
Me.[AddressTextBox] =
Nz(DLookup("[Address]","[TableName]","[NameFieldNameInTable] = '" &
Me.[NameTextBox] & "'"),"")
End if