Thread: the word 'надо' in sentences

See below.

Originally Posted by tiudavidharris

Are the following correct?

'Вчера мне надо было работать.'
this means 'yesterday, i had to work.'

Correct! (I've just corrected your capitalization, and the comma is unnecessary here).

Originally Posted by tiudavidharris

'Мне надо работать'
this means 'i have to work'

Correct!

Originally Posted by tiudavidharris

завтра, Мне надо поработаю
this means 'tomorrow, i will have to work'

Wrong!
Завтра мне надо будет работать. You apply future tense to "надо", not to "работать", the latter is the infinitive and stays unchanged.
It's the same thing you do in English, isn't it? I will have to work (not "I have to will work").

"надо будет" or "будет надо" (both are possible) mean "will have to", or more precisely, "it will be necessary"

Originally Posted by tiudavidharris

каждый день, Мне надо буду работать
this means 'everyday, i will have to work'

Wrong!
Каждый день мне надо будет работать.

"будет" is not related to "мне", it is impersonal. Literally, "to me - it will be necessary" (not "I will", but "it will").

Надо = "it is necessary". English uses the "dummy" subject "it". Russian does not use any, so the structure is impersonal.