HELP! what does it mean to authroize your computer

hello i have some games and tv shows that my friends gave to me on y i pod video and then i want to put them on my i tunes. what do i do? transfer purcheses from My ( My Ipod) thn if i do then it says that i need to authorize my computer. what does that mean and should i do it. i mean i want to ge the game and tv shows off my i pod onto the i tunes so its like i bougt it. but i dont want to take the game and tv show off ,off my i pod. i just want to get then on my i tunes so they dont get deleted when i get more games or tv shows what should i do PLEASE HELP. thank you very much.