is there any way to add a custom field?
What you call "custom fields", we call "tags".
Below the movie title, there's "no tag" written in green. You can click on it to tag the movie with any words you want. Then, you'll use the tag filter from the filtered search to list all the movies tagged with the same word (the tag filter is an extra filter that you'll find by clicking the button "Add/Remove Filters").
and can my personal database collection be printed?
In the filtered search, you can click the button "Export this list" to export the list as a .txt file which you'll be able to print.