"Of" from Dutch to French?

Question

I don't know how to translate the word "of" to French in some cases?

Ik vroeg me af OF hij dat wel moest doen.

And you also have

Wil jij een ijsje OF heb je liever een wafel?

What's the difference between the 2 "OF" in French? In Dutch, it is called "nevenschikkend voegwoord" and "onderschikkend voegwoord". And what's the translation of it?

EDIT: I tried to translate it to English, but it may be wrongly translated.

I asked myself IF he should do that.

And the other:

Do you want an ice cream OR do you prefer a woffle?

Answer 1

In a sentence between two items at the same "level", "of" will be translated as "ou"

ja of nee

Wil jij een ijsje OF heb je liever een wafel?

=

oui ou non

Veux-tu une glace (crème glacée) OU préfères-tu une gaufre?

In French there is no construction where "ou" doesn't put the two items at the same level ("ou" is always a "conjonction de coordination"). Your first example is a "subordonnée" (bijzin in Dutch), which is then introduced by "si" in French.

Ik vroeg me af of hij dat wel moest doen.

Je me demandais s'il devait vraiment le faire.

Note that "s'il" is a contraction of "si il".