Basic Grammar

The basic word order for Japanese is Subject-Object-Verb. (When your sentences get more complex, they might have this kind of order: Subject-Time-Place-Object-Verb or Subject-Frequency-Time-Goal-Verb; but that's for later.)

Example:

Cats eat mice. neko wa nezumi o tabemasu.
neko=cat, nezumi=mice, tabemasu=eat; wa and o=sentence particles

Verb Groups
Ends in -u (but NOT -eru or -iru)
Ends in -ru (end in -eru or -iru)
Irregular: suru and kuru

Conjugating Verbs
This does tend to get a little confusing sometimes, so take your time and don't get overwhelmed or rush it.

Dictionary Form
-u verbs end in: -u, -ru, -tsu, -bu, -su, -mu, -nu, ku, -gu
Examples: kaku-to write, asobu- to play
-ru verbs end in -ru
Examples: miru-to see/watch, taberu-to eat
Irregular
suru-to do, kuru-to come
-MASU Form (somewhat formal positive present tense)
-u verbs: root+i+masu
Example: kakimasu-to write, asobimasu-to play
-ru verbs: root+masu
Example: mimasu-to see/watch, tabemasu-to eat
Irregular: suru-->shimasu-to do, kuru-->kimasu-to come
-MASEN Form (somewhat formal negative present tense)
Same conjugation as -MASU
-MASHITA Form (somewhat formal positive past tense)
Same conjugation as -MASU
-MASENDESHITA Form (somewhat formal negative past tense)
Same conjugation as -MASU

-MASHOO (Let's...)
-MASU Form but replace -MASU with -MASHOO
-u verbs
Examples: kakimashoo-let's write, asobimashoo-let's play
-ru verbs
Examples: mimashoo-let's see/watch, tabemashoo-let's eat
Irregular
Examples: shimashoo-let's..(do...), kiru-to come (you don't say "let's come to...)

There's lot's more, but I think I'll leave it here for now...