How long will it take me to get a toned stomach after being so ill?

hello in tasha 17 and female. ok so i have had cancer for about 5 years and now its gone HORAYY! but in that time ive done quite honestly no exercise because i have been so ill, i use to be a dancer and do lots and i had a six pack now its all gone :( although ive done nothing im still very thin. my belly isnt "fat" but i do seem to have this little falbby bit just under my belly button :) what i would like to know is how do i get my body back?? and how long will it take to get a toned belly if i do all the right things?? :D