Japanese grammar is quite simple and straight forward but very different from English grammar so most English speakers find it rather confusing. For instance, the verb always comes at the end. The best thing you can do when learning Japanese grammar is to learn it from the bottom up and not compare it to English grammar.
Japanese grammar uses what we will refer to as particles to mark the various parts of the sentence. The main particles are: (These particles will be described in more detail below)
は wa
(as mentioned in lesson 1, the Hiragana "ha" is pronounced "wa" when it immediately follows the topic) topic marker
が ga subject marker
を wo
(pronounced "o") direct object marker
に ni direction marker, time marker, indirect object marker
へ e
(as mentioned in lesson 1, the Hiragana "he" is pronounced "e" when it immediately follows a place or direction) direction marker
The particles "wa" (は) and "ga" (が): The particle "wa" marks the topic of the sentence and the particle "ga" marks the subject of the sentence. In the example, "I know where you live" (watashi wa anata ga doko ni sunde iru ka shitte iru), "I" would be the topic while "you" would be the subject.
Not all sentences have both a topic and subject and, in many cases, the topic is implied in Japanese (for example, the "I" (watashi wa) would be left out of this sentence because it is implied that since I am talking I am the one that knows where you live). Many Japanese books and teachers teach that "wa" and "ga" are the same thing and it doesn't matter which you use when. This is not the case but I wouldn't worry too much about keeping them straight at first.
The particle "wo" (を): The particle "wo" (or "o") marks the direct object of the sentence. In the example, "I'm going to take her home" (watashi wa kanojo wo ie ni okuru), "her" would be the direct object.
The particle "ni" (に): The particle "ni" can be used to mark the direction, time, or the indirect object of a sentence.
An example of a direction marker can be seen in the previous example "I'm going to take her home" (watashi wa kanojo wo ie ni okuru). In this case, the "ni" acts like a "to" - "I'm going to take her 'to' home". The particle "e" (へ) can be used in this way as well but usually implies more of a general direction as opposed to a specific places.
The particle "ni" is also used to mark time in a sentence. For example, "I'm leaving at 3 o'clock" (watashi wa sanji ni hanareru).
The final use for the particle "ni" is that of indirect object marker. In the example, "I was taken home by him" (watashi wa kare ni ie made okurareta), "him" is the indirect object.
Note: The "watashi wa" in all of the example sentenced used above would normally be left out as it is implied.
