how can text be added to imovie

OK. That helps.

For this, the simplest solution would be to use iMovie Titles.

Open your movie in iMovie.app (or import it if it's not already there), then select the Titles option in the toolbar at the top.

Here you can see a number of different Title styles (static, animated, positional, etc.). Simply drag any one to the timeline window at the bottom - you can position the start and end times to align with the audio of the movie.

Simply add more Titles for each piece of text you want. Then save your movie (via File -> Share -> File... )

Your Mac should already come with iMovie, a fairly easy, yet comprehensive video editing app.

While it is geared more towards editing multiple clips and compositing a final video, it's more than capable of adding a text track to an existing video.

Check /Applications for iMovie.app

I guess I should have asked for clarification of your needs, because 'adding text' to a movie could be interpreted several ways.

Are you looking for titles or credits (typically played at the beginning/end of the movie)?

Or are you looking to animate text?

Or trying to add a text overlay, indicating the dialog/narrative? e.g. closed captioning or subtitles?

Or a translation layer for foreign language translations?

All of these could be considered 'adding text' to a movie. Need to know more about what your goal is.