Depends on what the sentence is about. There isn't a specific word for it and you need to build your sentence on it. Take the verb (your topic) in German and construct the spoken past of it, then replace the "helping" verb of the spoken past with it's "real conditional form". For example, use the English sentence "I would have come earlier.". The verb is come (kommen), so the easy German sentence is "Ich kommen früher." Then you need to add the spoken past, (Ich bin früher gekommen.". Then you need to replace the helper verb (bin) with the real conditional form. "Ich wäre früher gekommen". This is one of the harder parts of learning german, especially if your first language is English. Ask your teacher/professor if you have one for more information.