What you are asking for is to freeze a frame and then insert text.

To do so you can:
1. Move the slider to the frame in the Timeline that you want to freeze.
2. From the Tools menu, click Take Snap and save it to a file.
3. From the File menu, click Open File to add the snap to the Collections window.
4. Split the Timeline at the slider position.
5. Introduce the snap between the split.
6. Resize the snap to the duration for which you want to freeze the frame.

Now you can use the Text/Title effect over the snap to add text.