I have wiped the old persons data and photos etc off my recently purchased ipod touch and now all the display shows is a usb lead and CD, please can someone tell me how to get past this screen so I can transfer my own music

Please can anyone help, I recently purchased a second hand ipod touch and it had over 4000 photos on it, so to delete them I went to settings and found an option which said something like erase all content and data, I did this and the next morning I tried to turn it on to put my own music on, only to find that the only display on the screen is a usb lead with an arrow pointing to a CD. I cant get past this screen even after plugging it in to my itunes account, its like my computer can not find the ipod.