First, Merry Christmas first to all themy friends here. First, Merry Christmas to all my friends here.

First, Merry Christmas first to all theof my friends here. First, Merry Christmas to all of my friends here.

Your sentence is correct but this is more how'd we say it in the US.

First of all, Merry Christmas first to all theof my friends here. First of all, Merry Christmas to all of my friends here.

a lot more natural, although your wording wasn't wrong

In fact, I nearly forgeot it'lld be Christmas Day tomorrow, which was a [long dreaming day when I was in 20th]. In fact, I nearly forgot it'd be Christmas Day tomorrow, which was a [long dreaming day when I was in 20th].

“A long dreaming day” sounds like you spent the entire day dreaming. Is this what you mean? “20th” usually means “the 20th day of the month,” but I doubt this is what you mean.

In fact, I nearly forgeot that it'll be Christmas Day tomorrow, which was a long dreamingy day when I was in 20thmy 20s. In fact, I nearly forgot that it'll be Christmas Day tomorrow, which was a long dreamy day when I was in my 20s.

I'm not sure what you mean by "long dreaming day" so this is my best guess.

I clearly remember a Christmas eEve day around 2005 when I went on the street with my then-girlfriend about in 2005. I clearly remember a Christmas Eve day around 2005 when I went on the street with my then-girlfriend.

I clearly remember a Christmas eEve day when Iaround 2005 whent on the street with my then- girlfriend about in 2005nd I went out. I clearly remember a Christmas Eve around 2005 when my then girlfriend and I went out.

I clearly remember a Christmas eEve day when I went on the street with my then-girlfriend about in 2005. I clearly remember a Christmas Eve day when I went on the street with my then-girlfriend about in 2005.

We planned to sell some Christmas accessories like LED lights, Christmas hats, and sparklers onlyjust for fun. We planned to sell some Christmas accessories like LED lights, Christmas hats, and sparklers just for fun.

"only for fun" is not grammatically wrong, but it's a lot more natural to say "just for fun"

Unfortunately, we sold nothing out, so we used partsome of them ourselves and left the rest back (at) home. Unfortunately, we sold nothing out, so we used some of them ourselves and left the rest back (at) home.

“Sold out” means “卖光”, so “sold nothing out” implies that you sold many things, but you still had some of each item left unsold. Is this what you mean? Or do you mean that you didn’t sell anything at all (卖不出去)?

Unfortunately, we sold nothing out, so we used partsome of them ourselves and left the rest back home. Unfortunately, we sold nothing, so we used some of them ourselves and left the rest back home.

Unfortunately, we sold nodidn't sell anything out, so we used partsome of them ourselves and left the rest back home. Unfortunately, we didn't sell anything, so we used some of them ourselves and left the rest back home.

The next year, I gave some of the restmaining Christmas accessories to another girl. The next year, I gave some of the remaining Christmas accessories to another girl.

The next year, I gave some of the rest Christmas accessories to another girl. The next year, I gave some of the rest to another girl.

また、 The next year, I gave some of the remaining Christmas accessories to another girl.