There's two ways to go about this. You can either hit the quote button near the upper right of someone's post and it will automatically quote the whole post. You can then just delete anything in that post that you don't want to quote except for the quote html.
Alternatively if you want to copy and paste you can find the quote button next to the bold/italic/underlined buttons and then you just put your content in between the "quote signs". This same effect can also be achieved by simply typing out the word "quote" in brackets and ending the quote with "/quote" in brackets. It's the same thing, except the first way does types it out for you. If you want to add the name of the person you're quoting then the first set of brackets would have "quote=person" in the brackets. Don't worry about the "stupid question," I recall myself not knowing how for a little bit myself.
"Science without religion is lame. Religion without science is blind" - Albert Einstein
"The Mighty One appears, the horizon shines. Atum appears on the smell of his censing, the Sunshine- god has risen in the sky, the Mansion of the pyramidion is in joy and all its inmates are assembled, a voice calls out within the shrine, shouting reverberates around the Netherworld." - Egyptian Book of the Dead
"Man fears time, but time fears the Pyramids" - 9th century Arab proverb