Japanese Verb Conjugation

This is getting a little difficult for me to wrap my head around. About.com has great resources on learning japanese, especially this page on verb conjugation. I'll do my best to apply it here.

~NON-PAST~
Informal
The standard dictionary form ending in u, such as ataeru

Formal
U = -u +imasu
kaku -> kakimasu
RU = -ru +masu
taberu -> tabemasu
KURU/SURU = kimasu/shimasu




Negative Formal
masu -> masen
Negative Informal
u/ru -> anai/nai


~PAST TENSE~

Formal
U = -u +imashita
nomu -> nomimashita
IRU/ERU = -ru +masthia
ukeru -> ukemashita
KURU/SURU = kimashita/shimashita

Informal
...too be continued...