You might (if you're an anime nut) already be able to make a few one-word sentences: "Gomen nasai." ("Sorry."), "Konnichiwa." ("Good day."), "Tasukete!" ("Help!"), and maybe even "Ranma no Baka." But what say we learn some grammar.
You now know more than most of the world's population about Japanese grammar. That wasn't so bad, was it?
While we're here, take note: "desu" is the general "to be" verb in Japanese, so it's very useful. It covers the same ground as "is", "are", and "am" in English, and if you listen closely, you'll hear it a lot in anime.
Just one important thing: Although people (me) will tell you there are no silent letters in Japanese, they're sort of lying--in this (and pretty much only this) case, the "u" at the end is usually not pronounced (much, anyway). So you'll usually hear "des" instead of "desu", and it's ok to say it that way.
The next important thing to know about Japanese is that there aren't any articles--"a", "an", and "the" are nowhere to be found. So, in the sentence "Kore wa uchuusen desu.", there is nothing that takes the place of "a" in the English "a starship". It's just "starship".
Ok, so now you might be wondering what's with that "wa" sitting in "Kore wa uchuusen desu." That's part three of our basic grammar lesson. Japanese may not have articles, but they do have something usually called a "particle".
Particles are little words with no meaning that are used to mark different parts of a sentence or connect words. "Wa" is a particle used to mark the subject of a sentence. The only tricky part of this is that it comes after the subject; the same holds true for other particles and the different parts of a sentence that they mark, but don't worry about those quite yet.
So, in the sentence "Kore wa uchuusen desu.", we have "Kore", which we know is the subject not only because it is at the beginning of the sentence, but also (and more importantly) because it is followed by "wa". Then comes the object, "uchuusen", and finally the "is" verb, "desu".
Take note that it's usually better to pay attention to "wa" (and other particles once you learn them) than to where a word is in the sentence, because Japanese is rather flexible about word order. Worse yet, Japanese speakers have a tendency to drop the subject of a sentence if it's clear what the topic of conversation is.
For example, let's say you were standing around admiring a huge piece of machinery, wondering what it was. Since it's obvious what you're talking about, it wouldn't be strange for the person you're talking to just say "Uchuusen desu." (literally, "Is spaceship."). This is about the equivalent of saying "It's a spaceship." in English.
Another situation where it's common to leave out the subject is when you're talking about yourself. Unlike in English, it's not necessary to say "I...", "I...", "I..." in a conversation. Since you're probably wondering, "watashi" means "I" (and also "me"--there's no difference in Japanese), so remember it.
You already know what a katana is (I hope--a curved Samurai sword, right?), so this sentence would mean "This is a katana."
In the first three sentences, only the objects are new, and you probably already recognize the first two. And yes, "pen" (with a Japanese accent) means "pen"--you'll be seeing a lot of words like that. In the third sentence, the subject ("kore" in this case) has been left out, so it must be clear what the person who said it is talking about (no, not clear to you right now, clear to whoever they're talking to).
4 and 5 are both ways to introduce yourself, and mean the same thing (although 5 is a bit more informal than 4). Remember, if it's clear you're talking about yourself, you don't have to say "watashi wa" in this and many other situations.
In 6, 7, and 8, we're using "watashi" again, but this time instead of a name, we're using different words to describe ourself. Note that although English would use "a", "the", or "an" depending on the noun in these sentences, there is no difference in Japanese.
And that's it for your start in grammar. Oversimplified points to remember: Verb comes at the end, there is no "the", and "wa" doesn't mean anything. In part 2, we'll learn how to be egotistical and talk about ourselves.