CX2D will automatically create as many pages as necessary for all your chapters, so, with 10 per page, there will be 3 pages of chapters for a total of 30. Each page will have either a symbol or text, depending on the template used, that you can choose to go to another page. Text navigation usually uses the words Next or Prev(ious). Symbols are usually some form of an arrow pointing right to go to the next page or left for the previous page.
You can get an idea of what your menus will look like before you convert. Click on Tree View in the manual, notice the red numbers beside each line. Make sure the Video Preview window is open in CX2D, expand the CX2D window as in the manual, click on item 1 to see what the title menu will look like, then click on items 17-19 to see what the root, chapters and settings menus will look like. You can try several different templates to see which you like best.