As soon as you 'loaded' the cursor with text, you can place this text inside the current margins by clicking once near the top left (holding Shift will automatically add pages as well). But you can also create a new frame on any position you want by click-and-dragging the outline of the frame. If you release the mouse button and there is still more text to be placed, you will see a red "out box" at the bottom right of the last frame. Click on that to re-load the cursor and drag a new frame, where the rest of the text will flow into.

On the PC, you can hold Alt down to keep the cursor loaded with text after drawing a frame -- on your Mac it's probably the Option key. The cursor will change to reflect the new state.