Beginner grammar is the trickiest at first but also essential for sentences. When I learned about the structure of English contrasted with Japanese, it clicked for me.
English uses Subject-Verb-Object (SVO) structure: "I eat cake."
Japanese uses Subject-Object-Verb (SOV): 「私はケキを食べます」(watashi wa keki o tabemasu)
(I cake eat) or really, (As for me, cake, eat) but it's futile to try to be too literal in translation. The gist of it is Yoda speak, his sentence pattern is inspired by Japanese. For me, thinking of it in a simplified form, "I cake eat" and ignoring the oddness of the English equivelent, helped a lot. (NOTE: を wo is read as "o" when used as a particle in grammar.)
I learned this SOV principle from A Dictionary of Basic Japanese Grammar, a resource I would certainly recommend if you want to acquire anything past the very basic level of Japanese. (The Italics are an amazon link)
Japanese sentences are unique from English in that they only require a verb to be valid. Many things can be dropped if implicitly understood from context, and this is not just casually understood, but often formally correct too. Sometimes in informal usage, the verb can be dropped if the context only demands a subject or topic, but let's focus on sentences with verbs for now.
As seen above, the verbs come at the end in Japanese, and a very basic sentence indicates the state of being (using a copula verb: to be). In Japanese the polite form is です (desu), prononuced "des," for example:
「ねこです。」 ("Neko desu.")
This simple sentences means "(It/There/He/She) is a cat." It has no pronoun, which is common, because they are generally implied.
The most useful pronoun will be "I/me" which is わたし (私) (watashi). To use this pronoune in the sentence we need another particle, the ubiquitous は。Here is a curious point, in words this is pronunced as "ha" but in grammar it is always "wa," that sounds weird, but it's usually very easy to tell in real examples.
わたしはねこです。（私は猫です。）watashi wa neko desu. "I am a cat."
You can see here, why kanji is used: it makes it much easier to read as it provides a natural break between words in written Japanese. After learning hiragana, you'll find picking up the extremely common kanji to be irresistably easy, so don't worry about it early on.