I had the reverse problem with my daughter. She has some formal education but we also got for her many movies with the sound and subtitle both in English and Spanish.
My recommendation for you is to see the movie a few times:
1) In Spanish with the subtitles in English: So you can cheat when you don't understand what is happening
2) In Spanish with the subtitles in Spanish: It's easier to understand the written form.
3) In Spanish without subtitles.
Perhaps try seen a few movies in mode 1 and 2, and when it's too easy switch to mode 2 and 3, or just mode 3.
Don't expect word by word translations/subtitles. They help but they are not literal.
Later, it would be good to find some movies where the original sound is in Spanish (again, pick a DVD with the sound and subtitles in both languages). Be aware that each country has a different accent, so changing the country the movie is from will make a big difference that may be interesting.
[Also, try to get some formal knowledge about grammar and orthography from other sources.]