After a very long time, I rode roller-skates in a very long time today.

I think the last time I did this was when I was in second grade in elementary school.

We arrived in there earlier than the opening time so we had to wait a little bit.

After we got the skates and put our feet on the floor, everyone struggled to get used to balance their body and go forward.

It took me a few minutes but I soon got used to it soon.

I didn't expect this wouldto be fun but I really enjoyed it.

I felt like I went back to my childhood and haung out with friends in a very childish way.

I think I forgot the fun of doing something physically because I sait on my chair for a long time and study every day.

I want to go to an ice skating rink with friends sometime soon.

I rode roller-skates infor a very long time today.

I think the last time I did this was when I was in second grade in elementary school.

"this" refers to the subject of the previous sentence (rollerskating)

I went to the roller-skating rink with my friends and a teacher infrom class.

Not so clear if you went with your class as a class trip or just with this singular teacher and friends

We arrived in there earlier than the opening time so we had to wait a little bit.

After we got the skates and put our feet on the floor, everyone struggled to get used to balancefind their bodyalance and go forward.

That is the expression I would use