Reflexive pronouns (myself, yourself, etc) are more common in German than in English, because there are many more verbs that require them. (Reflexive verbs will be covered in Section V.12.) By default, a reflexive pronoun is the direct or indirect object of a verb, so it can only take the accusative or dative case. As you can see, there's a great deal of overlap between the reflexive pronouns and the personal pronouns:

By the way, those plural forms can also be used to mean “each other” or “one another.” For example, “wir sehen uns” doesn’t mean that we'll see ourselves, it means we’ll see each other – or translating more idiomatically, “see you later.”