I give naturally correct :)
how about your work? it's busy fun?
Have a nice day :)

Janalisa, I'm sure you have already known this but may I explain you for more naturally used. It's correct that you used "แล้ว" to indicate past tense. But we usually use it when we want to emphasize the situation. The direct translation for แล้ว is "already"
เขาไปหรือยัง ? เขาไปแล้ว
ฉันรู้แล้วไม่ต้องอธิบาย (I have already known, no need to explain.)
อิ่มแล้วไม่ต้องตักให้อีก (I'm already full. Please do not offer me any food.)
Hope this explanation doesn't make you more confused.^-^

Thanks again for the corrections, big HDV.

I'm afraid I'm a little confused about ก็ and ก็เลย... I think I understand now when I should use ก็เลย, which means "and so", or "therefore", right? But I can't quite grasp when you should or shouldn't use ก็. I know it's used for a lot of different things, and it's probably difficult to explain... But I wonder if anyone could give me some examples of different ways ก็ is used?

Jinny, I understand what แล้ว means, but I guess I was confused because it's not possible to express the "past within the past" in Thai like we would in English. In English I can add the word "already" to emphasize that the umbrellas were at my house before the time when I thought about buying another one. I just wasn't sure if this was clear in my Thai sentence, which is why I included the English translation. But I guess Thai sentences just don't need to be as precise about tense as English ones do.

Janalisa, sorry, I just saw your sentence with the English translation "แต่ที่บ้านมีร่มสองคันแล้ว (I already had two umbrellas at home)". This one is correct. I think you know how to use แล้ว perfectly.
About "ก็", it can be translated as "also, too" or means "to direct, to command".
ปิติชอบภาษาอังกฤษ ชูใจก็ชอบภาษาอังกฤษ (also, too)
คุณพ่อไปตลาด คุณแม่ก็ไปตลาด (also, too)
หนังสือเล่มนี้น่าสนใจ เล่มนั้นก็น่าสนใจ (also, too)
A : ฉันอยากดูหนังเรื่องนั้น B : ก็ดูสิ (to direct, to command)
A : ฉันจะไปดูหนังนะวันนี้ B : ใครห้ามเธอล่ะ ก็ไปสิ (to direct, to command)
A : (ฉัน)ยังไม่ได้ทำการบ้านเลย B : ก็ทำตอนนี้เลยสิ

ก็...สิ is used with close friends, family members and younger people.

These are what I can think of now. If any Thai friends have more examples please help.

Thanks Jinny! I didn't know about the use of ก็ in commands, so that's really helpful. So, I guess unless it's being used in that way, ก็ basically always means "also"? For some reason I had the impression it had lots of different uses, but maybe it's just me.