Having learned how to write words in hiragana, the next step is learning how to write sentences. This requires that you first learn some conventions for writing the so-called "particles."
There are two types of particles that you will learn in Japanese I, namely Sentence Particles (introduced in Lesson 1 of JSL) and Phrasal Particles (introduced in Lesson 4 of JSL). Sentence particles are written just as they are spoken - it is just the phrasal particles you need to pay attention to here. (Note that this is simply a a brief explanation of how to write the particles; you don't have to learn the function of the following particles yet! They will be thoroughly introduced in Lesson 4.)
The topic particle /wa/ is written with は (instead of わ).
The direction particle /e/ is written with へ (instead of え).
The direct object particle /o/ is written with を (instead of お).
In Japanese, the punctuation mark that is comparable to the English comma is "、" and the Japanese equivalent of the English period is "。".
Japanese people write sentences vertically as well as horizontally. For Japanese I and II, you can write sentences horizontally, unless your teacher asks you to write vertically.