Hi Salim! If you are in the default setting, you are in Add Clones mode. This means you should be able to just drag downwards on any of your white original drawings in the x-sheet. That produces light brown “clones” – that is your drawing being held for the number of frames that you drag down. If you do too many you can drag clones upwards again to make them go away.
In “Slide mode” you can drag your originals up or down through the “sea of clones” 🙂
But check out the tutorial videos – it looks like you would benefit from watching them.