Thank you for the link.
(Here's a better one, same page, but this one opens: Fortune City). The page reads:
It should be noted that sometimes is an adverb of frequency, whereas sometime is an adverb of time.
Ex: I sometimes see him in the park.
Ex: I would like to read that book sometime.
In the first example, the adverb of frequency sometimes occupies the middle position of a clause.
In the second example, the adverb of time sometime occupies the end position of a clause.
The adverb sometimes (note the -s) can occur in three positions: at the beginning of the sentence, at the end of the sentence, and between the subject and the verb.
Does that help?