Just a little question

In Japanese is there an equivalent of this..

For example

I'm sending your present tomorrow.

or I'm going to Napoli tomorrow.

would you just say something something like

明日はナポリに行きます

Which is basically tomorrow I'll go to Napoli.

The thing that I'm wondering about is the ing part. I know that ing is teiru in Japanese but in English ing can be used for the future tense as well. So in Japanese is there any equivalent or do I just stick with the root form of the verb

"...ing" in English has different meanings, as you say, as (1) doing something, and (2) intends to do something (soon). And in that sense "...ing" does not correspond exactly with "....te iru."

To say "I am going to Napoli tomorrow," you can say:

明日ナポリに行きます。with just the "...masu" form of the verb, because "...masu" form is for now and future (anything that has not happened),

or, if you want to emphasize that you "intend to do something," or that it is very soon, you can also say:

- 明日ナポリに行くつもりです。(I intend to go to Napoli tomorrow.)
- 明日にもナポリに行くつもりです。 (I intend to go to Napoli soon, as soon as tomorrow.)
- 明日ナポリに行くところです。(I am about to go to Napoli tomorrow.)
etc.