Help understanding pushing a 35mm film when shooting?

I can't develop film myself. I send it to a lab.

If I use a film, let's say Ektar 100, and set my 35mm Nikon to 400 ASA, shoot the roll, and then send it to the lab with a note that asks for process for 400 ASA…

Is that pushing 100 to 400?

As for why… I'm just trying to learn, and I'd like to get some grain in there. Lol!

Yes, that is pushing from 100 to 400

That would be a TWO stop push of the development process. Here is how it breaks down. Each one stop is a doubling of the ISO. So if you start with ISO 100, one stop more exposure (or push) would be 100 x 2, or ISO 200. Now a two stop push would be doubling the 200, which would be 400. A three stop push would mean you have to double the ISO 400 rating up to ISO 800. A four stop push would be ISO 1600. Most pro level labs charge extra for each stop of push, so it is good to know how many actual stops of push you are using.

By the way, just pushing the film from 100 to 400 is not really going to give you grain. Grain is an aspect of naturally high ISO film. If you want grain, use a film that is actually ISO 800 or higher.

The sole intent of Ektar 100 is smooth grain free images. You are totally defeating the purpose and design of the film trying to force grain out of it, which again, you are not really going to do by just shooting it at ISO 400.In fact, Ektar is rather touchy about exposure, much like slide film. You are probably going to be quite disappointed in your photos by doing the push to the film.

Here are some shots with ISO 1600 Ilford black and white film outdoors with a neutral density and red filter over the lens. (The full size photos have much more grain than what is seen in these downsized images, but you get the idea).

http://www.lightanon.com/-/lightanon/gallery.asp?cat=144825