to have just done something = Spanish acabar de + infinitive
First of all, a note about the translation into English: when you've just done something, American English usually uses the simple past, for example: "I just spoke to him" while UK English usually uses the present perfect: "I've just spoken to him". I'll use them both in these examples. We're talking about how to express something that you've done very recently. Here are some examples using the "acabar de + infitive" structure:
Spanish - presente
1. Acabo de hablar con Juan.
2. Ella acaba de volver del trabajo.
3. Acabamos de terminar de pintar la casa.
English - present
1. I just spoke to Juan / I've just spoken to Juan.
2. She just came back from work / She's just come back from work
3. We just painted the house / We've just painted the house.
You can use the same structure talking about something that happened in the past with the imperfect (acababa de):
Spanish - pasado
1. Yo acababa de hablar con Juan cuando llegó María.
2. Ella acababa de volver del trabajo cuando se dio cuenta de que había olvidado su bolso.
3. Acabábamos de pintar la casa cuando empezó a llover.
English - past
1. I had just spoken to Juan when María arrived.
2. She had just come back from work when she realized that she had forgotten her handbag.
3. We had just painted the house when it began to rain.
Notice that in the past form US English and UK English are the same.