In each of the pages you have, there is a "page order" field. The lower the page number, the earlier it shows.

I like to set my page orders up in increments of 5.

5,10,15,20,25, etc.

(This gives me flexibility if I want to rearrange later.)

When you log into your Wordpress administration area, and click on "Pages", click on "all pages".

Click on the "Quick Edit" link underneath a page title.  It will expand a window, and then you'll see that one of the options is called "order".

That's the page order.

It's also on the full edit page as well, on the right margin.

I believe it would be somewhere under the "publish post" or "update" button.