How do I differentiate between haben and sein verbs when using perfect past?

When using perfect past, you should form your sentence with both an auxiliary verb (haben/sein) and the past participle of your chosen doing word.e.g. Person + auxilliary verb + details + past participle. Each verb has a specific auxiliary verb, and if used incorrectly it can change the meaning of the sentence. In order to get it right 99% of the time, think of movement. If your chosen verb involves moving from one place or state to another, it most likely requires you to use sein. For example, I travelled to Germany = Ich bin nach Deutschland gefahren. Don't forget to conjugate sein/haben depending on who is doing the verb e.g. I travelled... ich bin nach Deutschland gefahren, she/he travelled, er/sie ist nach Deutschland gefahren, they travelled, sie sind nach Deutschland gefahren. If the verb does not involve movement, for example to see, you would always use haben. Don't forget to conjugate this too! So...I saw a film Ich habe ein Film gesehen He/She saw a film Er/sie hat ein Film gesehen They saw a film Sie haben ein Film gesehen. If you're still stuck after the movement rule and can't figure it out: go with haben! The majority of german verbs require the auxiliary haben, so it's your best bet, just make sure you conjugate it correctly (you should definitely learn all six conjugations of haben and sein for help with reading, writing and listening so you can tell who is doing the verb!)Haben - Ich habe, Du hast, Er/Sie/Es Hat, Wir haben, Ihr habt, Sie/sie haben Sein - Ich bin, Du bist, Er/sie/es ist, wir sind, ihr seid. Sie/sie sind