Use the verb ser in the imperfect tense to describe how you used to be when you were little. use action verbs in the imperfect tense to describe what you used to do when you were little.

1. Cuando era pequena, era rubia, pero ahora mi pelo ya no es rubio.
This sentence means - When I was a little girl, I was blonde, but my hair is not blonde anymore. As you can see, I used the verb SER in the imperfect tense (ERA). Ser is an irregular verb, which means that its conjugations have to be learned by heart - era, eras, era, eramos, erais, eran.

2. Yo amaba jugar con mis amigos y amigas, y yo iba a sus casas para jugar con ellos. 
This sentence means - I loved playing with my friends, and I went to their house to play with them. As you can see, I used the verbs AMAR and IR in the imperfect tense (AMABA and IBA) which is used to describe events in the past.