Verb conjugation of "prallen" in German

I have contacted you 12 months ago to propose your school's inclusion in our language school directory. I wanted to inform you that our site achieved high positions in search engines last month.
I have even met someone who invited me to come and visit. It was an older couple who were renting apartments for language students. Well, actually there are agencies that offer the same as this couple, but I'm open.
I am in my German lesson and I'm learning about the subjunctive. I had never heard about it before. Can you ever deal with all Verb conjugations? I just totally misunderstand the past tense!