These tenses are extremely easy, so I'm going to condense this into one chapter. This is to allow us to hit Subjunctive past and the two perfect tenses to it sooner.
Conditional:
Conditional is the tense that describes what "could" happen. It's easy to mix it up with the Subjunctive - I never did, but others do because the ideas are fairly similar - but conditional is an indicative tense, meaning a good way to think about it is that something "definitely could/could not". It's a lot easier than Subjunctive because we have this tense in English and use it all the time. For example:
Yo comería mañana. ｜I could eat tomorrow.
Me gustaría comer contigo. ｜I would like to eat with you.
To make a conditional stem, you use the verbal infinitive + the ending, just like in simple future. Here are the endings:
Yo: -ía
Tú: -ías
Él, ella, ud.: -ía
Nosotros: -íamos
Vosotros: -íais
Ellos/ellas, uds.: -ían
Conditional Perfect
Conditional Perfect is often viewed as the past tense of conditional, since haber operates as an auxiliary verb here. Conditional Perfect in English is the tense that states that someone "could have" done something, but didn't for some reason. The conjugation of haber is the conditional, which translates to "could have" in English, and it is followed by the past participle, as is customary for perfect tenses. Conditional perfect examples will be given after the conjugations, but let's see them below:
Yo: Habría
Tú: Habrías
Él, ella, ud: Habría
Nosotros: Habríamos
Vosotros: Habríais
Ellos/ellas, uds: Habrían
Examples:
Habría comido hoy, pero estuve trabajando. ｜I could have eaten today, but I was working.
Habrías hablado, si había venido. ｜You could have spoken, if you had come.
Me habría gustado de comer contigo. ｜I would have liked to eat with you.
Habríamos sido amigos. ｜We could have been friends.
Habrían bailan juntos, pero estaban tímidos. ｜They could have danced together, but they were shy.