In order to form the conditional in French, you need to take the infinitive of the verb you want to use (e.g. manger - to eat) and add the ending depending on which pronoun you wish to use.
Je mangerAIS - I would eat
Tu mangerAIS - You would eat
Il / Elle mangerAIT - He/She would eat
Nous mangerions - We would eat
Vous mangeriez - You (plural or polite) would eat
Ils / Elles mangeraient - They would eat
However there are exceptions to the rule, with the irregular verbs you do not use their original infintive form however the endings remain the same.
Faire (to do) - Je ferAIS - I would do
Aller (to go) - J'irAIS - I would go
Etre (to be) - Je serAIS - I would be
Avoir (to have) - J'aurAIS - I would have
Pouvoir (to be able to) - Je pourrAIS - I would be able to
Devoir (to have to) - Je devrAIS - I would have to
Savoir (to know) - Je saurAIS - I would know
Vouloir (to want) - Je voudrAIS - I would likesee more
The accusative case should be used when there is a DIRECT OBJECT in the sentence. It is usually what the verb is 'doing', for example, the dog ate the bone. The bone would be the object and, therefore, in German you would use the accusative case (Der Hund isst DEN Knochen).
However, there are exceptions! You should not use the accusative case if the object follows the verb 'to be' (sein) e.g. I am a boy. Instead, you should use the nominative case. So it would be 'Ich bin EIN Junge' instead of 'Ich bin einen Junge'.see more