nsscrollview

If you already have an Xcode project, then (presumably) you already have a window in a storyboard or a XIB file. Go to that file and open up the Utilities panel on the right side of the IB window (View -> Show Utilities), then display the object library at the bottom (the 3rd of the 4 icons in the toolbar at the bottom) by clicking on it.

Look for the scroll view in the list of available objects. You can type "scrollview" in the text field that's now at the bottom to filter out the irrelevant items, if you want. Drag the scroll view object into your window (if XIB) or window view controller (if storyboard).

You have several other tasks to complete before this scroll view is useful (size it and add autolayout constraints, add an outlet to your code that refers to it, etc), but at least you have the scroll view you asked about.