I've started trying to understand the imperfective and perfective aspects of verbs, and how to use them. Although I'm still a little confused, I wrote some out. If they look in any way a little bit wrong or silly, please correct them. Some words I got from Google Translate, so it may not look completely accurate. Thanks in advance

Вчера, Жанна покупала 2 сумки. - yesterday, Zhanna was shopping for 2 bags. (But even though покупать means buy, it doesn't emphasize that she successfully bought it...Right? Even though the word does mean buy..)
Вчера, Жанна купила 2 сумки. - yesterday, Zhanna bought two bags.

сегодня Андрей пробежал марафон. - Today Andrei finished running a marathon.

посмотрим фильм с тобой. - We'll watch the entire movie with you.
Будем смотрим фильм с тобой поздно. - We'll watch the movie for a while later.