When would one use the locative? If the verb is in the locative?
Most common situation is after prepositions that govern the locative case.
- Nie myśl tylko o sobie (don't think only about yourself).
And would it be right to say "uczyłem się" for "I taught myself"?
uczyłem się (past tense, imperfective aspect) is more like
I was teaching myself or I was studying.
nauczyłem się (past tense, perfective aspect) means more like
I taught myself or I learned.
It takes some time to understand the differences between the perf. and imperf. aspects.
And when would you use "sam"?
It means
alone or
the same. It's declined by gender and case, like an adjective, also when it means 'the same'.
And when would you use "sam"?
Aha.. now I understand what you mean.
Sam = himself
Sama = herself