I have to go.

Watashi wa ikanakerebanaranai. : I have to go.
watashi : I
iku : go
(ika-nai,iki-masu, iku,iku-toki,ike-ba, ike)
ika-nakerebanaranai : must go, have to go/ has to go
ika-kakerebaikenai : must go, have to go/ has to go

Watashi wa repooto wo kakanakerebanaranai : I have to write a report.
repooto : report
kaku : write
(kaka-nai, kaki-masu,kaku, kaku-toki, ka-keba,kake)
kaka-nakerebanaranai : must write, have to write / has to write
kaka-nakerebaikenai : must write, have to write / has to write

Watashi wa kodomotachi no mendou o minakerebanaranai : I have to take care of children.
kodomo : child
kodomotachi : children
mendou : matter
miru : look, see
(mi-nai, mi-masu, miru, miru-toki, mire-ba, mi-ro)
mendou o miru : take care of
mendou o mi-nakerebanaranai : must/have/has to take care of

Anata wa ni ji madeni shigoto o katazukenakerebanaranai : You must finish your work by 2 o'clock.
anata : you(single)
ni : two
ji : o'clock
madeni : by
shigoto : work, job, assignment,mission
katazukeru : finish
(katazuke-nai, katazuke-masu, katazukeru, katazukeru-toki, katazukere-ba, katazuke-ro)
katazuke-nakerebanaranai : must/have/has to finish
Japanese word order : you,two,o'clock,work,must finish : You must finish your work by two o'clock.