Help (japanese language)?

Question:

I wanted to to know when do we change the "masu" to "ni" in verb,example:

nomimasu = nomini
tabemasu = tabeni
mimasu= mini

I want to know when do we apply them.Also if can,can you translate this:

Konban syokuji ga owatte kara, eiga o mini imasu.

Thanks(a beginner in japanese laguage)

Answer:

It's really replacing the 'masu', it's making the masu stem of the verb which acts more like a noun, then adding a proposition 'ni'.

In the example you've given it should be "eiga o mi ni iKimasu."
'ikimasu' as in 'to go', and 'ni' in this case acts like english 'to', we end up with the sentence pattern 'to go to *verb*"

So, 'eiga o mi ni ikimasu' is 'to go to watch a film'

As for the first part of the sentence, we have 'konban' which sets the time: this evening

The 'kara' in 'shokuji ga owatte kara' indicates 'after' (or as I think about it 'from') the previous part of the clause which means 'meal is finished'

So altogether i is "This evening, after I've finished dinner, I will go to watch a film"