For this what am I supposed to do?
Traduzca Vd. al espanol las expresiones en ingles.
1. Nosotros walked por las calles de la ciudad.
Do I just change the english verb to spanish ? OR do I translate the whole sentence into english?
Yes. Change the English verb to the Spanish verb.
And what do you choose? First of all, is it the Preterit (action) or Imperfect (description) and do you want the regular verb caminar or the irregular andar?