If you don't want to create a designated swap partition (e.g. if you plan to downsize it later) and don't want to play around with GPartEd, you can create a swapfile instead.
To create a 512 MiB swapfile, do the following:
dd if=/dev/zero of=/swapfile bs=1024K count=512 mkswap /swapfile swapon /swapfile
To automatically add the swapfile upon boot, add this line to the
/swapfile swap swap defaults 0 0
You can later easily change the size of the swapfile by re-creating a smaller or larger one.
You only have to make sure the file is contiguous or
swapon might give an error.