You might enjoy spending some time with the Pages User Guide. It's a free download from the Help menu. Very well written.
Chapter five talks about Adding Floating Text Boxes and Linking Text Boxes. You may get some idea from these two sections. you can put a floating box on each side of the page and have the text in the two act independently. Then they can be set to flow to the box in the same alignment on the next page.
If you don't need Table of Contents and other advanced options, you may prefer to use a Page Layout Template. If you decide to go that way, be sure to do some reading first so you get off on the right foot.
In a word processing document, the main text, placed in the text layer, acts as a single stream of characters from the beginning of the document to the end. Splitting pages into two or more columns makes that river of text enter the multi column page at the top of the leftmost column, continue until it gets to the end of the column, then jump to the top of the nect column on the right. When it reaches the end of the last column on the page, the text jumps to the next page and continues at the tp of the leftmost column on that page.
You can force the jump to the next column by inserting a column break (Insert menu > Column break) at any point in the text, just as you can force a jump to the next page by inserting a page break at any point.
If you want text to behave differently, you need to place that text into one or more text boxes, as described in the posts above.