The content of your page is completely independent of the layout and theme.
To change the layout of a page:
- Drag widgets around by their edit tab "grippy dots"
- Click "Page Layout" at the top of the page to change the layout
- Change the number of columns
- Change the width of columns
 
- Change the height and width of sections
- Add new sections
- Delete sections
 
- Move sections around
- Advanced "Page Layout" features:
- Layout widgets in background layers of the page (for this page only or for the theme)
- Freeform layout allows you to place widgets exactly where you want them
 
- Freeform layout allows you to resize widgets