ubun2

Other than adding new disks/partitions which you would format to swap, you can create swap files on regular filesystems. It is possible but highly discouraged to create these files on FUSE filesystems. Swap files also commonly break hibernate.
For more info, see manual pages on mkswap and swapon/swapoff. You probably want to add this permanently, so have a look in the manual page for fstab how a line for whichever swap type you decide to make should look like.