I would say these a little differently: 1. I am still taking lessons to improve my English. 2. I work at night so I got everything done then. 3. The festival only targets the young. 4. Due to the huge influx of people, there were several security checkpoints.

1) I still continue with my English lessons, in order to improve. 2) (not sure what you are trying so communicate here but I'll offer some suggestions) I worked all evening (or if you stayed up throughout the night you'd say.."I worked through the night") to prepare what was needed. 3) The festival aims at appealing to the young / the festival appeals predominantly to the young. 4) Due to the huge influx of people, various security measures were put in place ...., increased security measures were implemented