Yo contenta. what should go in the middle?

Estoy. As "I am okay" or "content." Estar means"to be". So since it's in the Yo form it's estoy.
Just in case you need other forms of Estar
Yo-Estoy
Tu-Estás
El Ella Usted-Está
Nosotros-Estamos
Ellos Ellas Ustedes-Estan

Hope this helped :)

3. study 4.eat 5.play american football 6.write a card 7.practice piano 8.swim in the pool 9.paint a mural 10.listen to the band 11.dance at a party 12.drink milk 13.visit panama 14.open the card 15.prepare dinner 16.stay in the house 17.watch tv 18.write on the paper 19.study spanish 20.examine the paintings in the museum. i hope this : )