Personal Pronouns Accusative

Each personal pronoun mainly appears in three different forms:

Casem.n.f.pl.pl.pl.Formal
NominativeichdueressiewirihrsieSie
AccusativemichdichihnessieunseuchsieSie
DativemirdirihmihnihrunseuchihnenIhnen

The genitive forms can be ignored until C1. Just a quick hint that might help you remembering the right form for the appropriate case: The he, it, she & also the plural forms contain the article ending:

NominativeAccusativeDative
er -> derihn -> denihm -> dem(m.)
es -> dasihm -> dem(n.)
sie -> dieihr -> der(f.)
sie (pl.) -> dieihnen -> den(pl.)

This topic is covered in: A1-L22