[subject] + 几乎 + [verb phrase] / [adjective]
几乎 + 所有的 / 每 + [noun] + 都 + [verb phrase]
[subject] + 几乎 + 不 / 没 + [verb]
几乎 means "almost": the claim is nearly true, but not quite. It goes before the verb or adjective, after the subject.
几乎 also goes in front of 每 or 所有的, and then the sentence needs 都 before the verb.
With 不 or 没 after it, 几乎 gives "hardly" or "almost nobody".
几乎 + verb can also mean something nearly happened and didn't.
差点儿 does the same job in speech and is the usual word for a near miss; it has its own point.
几乎 doesn't go in front of a pronoun subject.