Learn Portuguese (Portugal): A rapariga está a criar a imagem.

In European Portuguese, we build the present continuous (actions happening right now) by combining the verb estar (to be), the little word a, and the full dictionary form of the action verb. Here, we use está because we are talking about "the girl", followed by a, and then the infinitive verb criar (to create).

Does the a after está mean "to" or "at" here?

Normally the word a translates to "to" or "at", but in this specific grammar structure, it does not translate to a separate English word. It simply acts as the glue that connects the verb estar to the main action verb criar to show that the action is happening right now.

Why is it a imagem? I thought words ending in consonants were usually masculine.

That is a good rule of thumb, but words ending in -gem are a major exception! Almost all Portuguese nouns ending in -gem (like imagem, mensagem, and viagem) are actually feminine. That is why it uses the feminine word for "the", which is a.

I have heard other words for "girl" in Portuguese. Is rapariga the most common one?