do you really have 11+ partitions on your primary master drive?
"hda11" means it's looking at the 11th partition. if this is wrong and you *have* assigned a swap partition, then type from the command line (i'm pretty sure you'll need to be root):
"mkswap /dev/hda#" where "#" is the number of the swap partition. this will format the entire partition given as swap and then assign it to be mounted after next reboot. you can also use "swapon /dev/hda#" to turn it on right then, if you want, presumably. type "man mkswap" to check the manual pages for more info, if you'd like.
also, if you don't have a swap partition, you should be able to allocate a swap file with the name and location of your choice on your normal drive by using "mkswap /pathname/filename 131072"
this will create a 128 MB (131072 KB) swap file and set it up for use.
good luck! make sure to check "man mkswap" to be sure this is right, though, because i'm not certain YDL will work exactly the same as mandrake or debian, which i have experience with.