Posiłki

Na śniadanie zwykle jem jogurt z płatkami ale dziś wolę jeść bułkę z masłem i białym serem. Lubię pić sok pomarańczowy albo zieloną herbatę.

Na obiad jem sałatkę z pomidorami i ogórkami i piję wodę mineralną z cytryną. Potem jem lody waniliowy. [waniliowe]

Na kolację jem na pierwsze dane [danie] zupę "Barszcz" ze śmietaną i na drugie danie jem pierogi ruskie, też ze śmietaną. Piję komput [kompot] malinowy.

[Uczę się sam polskiego z książką - teraz na lekcji 8 :)]

Posiłki

Na śniadanie zwykle jem jogurt z płatkami, ale dziś wolę /wolałem zjeść bułkę z masłem i białym serem. Lubię pić sok pomarańczowy albo zieloną herbatę.

Na lunch jem /zjadłem sałatkę z pomidorami i ogórkami i piję /wypiłem wodę mineralną z cytryną. Potem jem /zjadłem lody waniliowe.

Na obiad jem /zjadłem na pierwsze danie zupę barszcz (barszcz is not capitalised; also saying "zupa barszcz" is like saying "spaghetti pasta") ze śmietaną, a na drugie danie jem (another "jem" so shortly after the previous one is unnecessary) pierogi ruskie, też ze śmietaną (really? I never heard of someone eating them like that). Piję /Wypiłem kompot malinowy.

[Sam się uczę (in this case this word order seems more natural, though what you wrote is grammatical as well) polskiego z podręcznika (technically, you could use the word "książka" here but "podręcznik" is more suitable) - teraz jetem w (or: przy) lekcji 8  (unless the book explicitly calls them "lekcje" - lessons, I feel it would be more appropriate to call them "tematy" - topics or "rozdziały" - chapters/units. And I'd say "w lekcji" -- wchich is quite unusual -- only because it's a lesson in a book, so it'd be following the same construction as "w rozdziale", "w temacie". But if it were a normal lesson with a teacher, it'd be "na lekcji") :)]

Great job!

Though you haven't gotten to the past tense yet, have you?

Anyway, using only the present tense gives the impression that it is what you eat and drink every day. Therefore in blue I wrote how the verbs would look like in the past tense so that the text is about what you ate today not what you eat every day:)

And concerning the names of the meals, I feel it's much more important what the meal is than what time it is eaten. Like even if I ate obiad at 9 p.m. I'd still call it obiad, regardless of the hour. I could say "Jem obiad na kolację" ("I'm eating dinner for supper") but it wouldn't change what the meal was, just what time I happened to eat it.

So obiad is basically dinner: a hot meal that usually consists of "zupa i drugie danie" ("soup and the second course") sometimes followed by a deser ("dessert").

Kolacja is considerably smaller and lighter than obiad. It's usually eaten cold. It could be kanapki (open sandwiches) or a jogurt (yogurt) or a sałatka (salad), etc.

Due to the fact that many people don't have a chance to eat dinner untill late afternoon or evening, many skip supper altogether.

But if you eat dinner late, you have to eat something to sustain yourself during the day, thus many people eat lunch. It's a considerably new trend so we don't have a Polish word for it, we just simply say "lunch".

You may have also heard the term "drugie śniadanie" ("second breakfast" and no, we're not hobbits ^^). If you eat a light breakfast and don't eat lunch, you tend to get hungry in the late morning.

So what you ate was lunch and dinner, not dinner and supper.

Wish you luck learning Polish! :)