In this week's vocabulary lesson (available here), you read:
I did look great in the new accessories. It's not a mistake, though. Of course, DID is used mainly to ask questions and form negative sentences in past simple, but it may also be used in positive ones when you want to stress the verb and make it sound stronger; then it's similar in meaning to 'really'. This rule applies not only to the past simple auxiliary DID, but also present simple. Take a look at these examples in present simple:
I do love you! How can you even think I don't? She does think you are not fair.
With other tenses (present perfect, present continuous, past continuous, future simple) you already use the respective auxiliary to form positive sentences. So, if you want to underline the meaning of the verb, you have to resort to intonation and stress the auxiliary verb.
Can you make your own sentence like this? Put it in the comments! :)