You can create several sheets in an .xmind file.
How to create a sheet in an .xmind file?
1) Open an .xmind file;
2) Tap「...」on the upper right corner of the map;
3) Tap「New sheet」to create a sheet.
How to switch between different sheets?
1) Open an .xmind file which has several sheets;
2) Tap the icon on the bottom left corner of the map to show the sheet panel;
3) Tap the sheet name to switch to the sheet;
4) Slide left the sheet name to rename/duplicate/delete the sheet.