The three conjugations
The verbs in portuguese have three conjugations:
The first (-ar), the second (- er*) and the third (-ir).
The conjugation suffix is ever the tonic syllable.
*The verb pôr is the revised form of the extincted poer.
Moods
Indicativ/Indicativo (In.di.ca.ti.vo)
A fact.
I walk.
- Eu ando.
The subject certainly walks.
Conjunctive/Subjuntivo (Sub.jun.ti.vo)
It is uncertain.
If I walk...
- Se eu andar...
The "if" shows uncertainly.
I hoped to walk.
- Eu esperava andar.
It's a wish, so, it isn't certainly.
When I want, I will walk.
- Quando eu quiser, eu vou andar. or (Quando eu quiser, eu irei andar. or Quando eu quiser, eu andarei.)
It' s more complicated to explain. When it has a relative pronoun, that is generally used to ask an explanation to the doubt of the first person, the conjunctive comes.
Maybe I walk...
- Talvez eu ande...
Maybe I wlll walk.
- Talvez eu vá andar. or (Talvez eu irei andar. or Talvez eu andarei.)
The "will" puts the action into the future.
He doesn't know if he will walk or no.
- Ele não sabe se (ele) vai andar ou não. or (Ele não sabe se (ele) irá andar ou não. or Ele não sabe se (ele) andará ou não.)
Imperative/Imperativo (Im.pe.ra.ti.vo)
It shows a supposition to what the first person do to another person do.
Let's walk there.
- Andemos para lá or Vamos andar para lá.
The first person is supposing to the other person that is with himself.
Walk two times a week in the beach and you will lose your weight.
- Anda duas vezes por semana na praia e perderás o teu peso ou Anda duas vezes por semana na praia e perderás teu peso
The first person is indicating to the second what he should do.
Don' t walk! You are prohibited!
- Não andes! Estás proibido!
The first person in forcing the second to don' t walk.
Conditional/Condicional (Con.di.ci:o.nal)
It shows what was in the subjunctive if the conjunctive come certainly, a hypothesis.
If you were fat, you would have to walk
- Se fosses gordo, precisarias de andar.
Be careful!
If by 2030 you are fat, you will have to walk
- Se em 2030 fores gordo , terás de andar.
It isn't a hypothesis, because the grammar future is uncertainly, the second person can be fat or not.
Nominal form(s)/Forma(s) nomina(l/is) (For.mas no.mi.nais)
It isn' t really a mood. It is the different forms that the verb can appear.