So I'm trying to learn Taiwanese Mandarin, and apparently they don't really use the neutral tone, but if that's the case how do you say things like 子,了, and 的?
I guess you are talking about 輕聲.
In addition to the first, second, third, and fourth tones, there is a 輕聲 (light tone) in Taiwan. It is also known as the fifth tone or the neutral tone.
The mark is a small dot. When the text is written vertically, it is marked at the top. In a horizontal print, it is marked on the left.
You can search 注音符號發音教學 on the YouTube site.
I think there must be some confusion here.
Neutral tones definitely exist in Taiwanese Mandarin.
There's even a paper here called A Study of Neutral-Tone Syllables in Taiwan Mandarin in which the contours of the neutral -le, -de and -zi are discussed in depth.