If I understand correctly, you want the first page of the document to not have a page number. You want the rest of the pages to have page numbers with the second page of the document beginning as page 2. You want the page number to appear centered in a header.
I’ll try to explain a simple process to obtain this.
First, open a new document.
Open the Sidebar if it is not open. This can be done by going to View in the Menu Bar and selecting Sidebar.
Open the Styles deck by clicking on the icon at the far right with the capital letter A and what looks like a paintbrush. At the top of the Styles deck are a number of icons. The fourth icon from the left is the Page Styles icon. Click on this. You should see a list of page styles with Default Page Style currently highlighted
The fourth style in the list says First Page. Double click on this style to select it. Your first page is now using the First Page page style.
Fill your first page with text until it overflows to the next page.
The Default Page Style should now be highlighted in the Sidebar. Right click on this and select Modify…. Go to the Header tab and click the box beside Header on. You really don’t need to worry about making any other changes on this tab. Click OK to close the dialog.
Now, click on the first icon on the left at the top of the Styles deck in the Sidebar. This opens the Paragraph Styles deck. You should see a list of paragraph styles with Default Paragraph Style highlighted.
Go down the list until you see Header and Footer. Click on the plus sign to the left of this.
You should now see two more paragraph styles listed below Header and Footer. Right click on the one that says Header and select Modify….
Go to the Alignment tab and select Center in the Options area. Click OK to close the dialog.
Click in the header area of your second page. The cursor should appear in the center. A light blue box should also appear reading Header (Default Page Style). Click on the small arrow at the right of this box. Select Insert Page Number. The number 2 should appear centered in your header.
As your text flows to the next page, a number 3 should appear centered in a header. Following pages should appear in a similar fashion with following page numbers.