Hi,
You appear to have enough free memory at the time, but in case you
need to make use of more intensive applications the following
URL has a tutorial on how to add swap on a file:
http://www.cyberciti.biz/faq/linux-a...ap-file-howto/
Your other alternative of course is create a partition for your
swap, but you may need to resize your partitions if you don't
have unallocated space.
Best regards,