problem creating swap on lvm2
 

I accidentaly deleted the swap (Logical Volume) and I can't create it back. I cannot set it's filesystem properties to swap (there's only) ext3, ext2 and GFS (local). I'm using system-config-lvm (I don't know how to work with other programs)

you will have to use fdisk to create the swap partition if you did delete the partition.

fdisk is only usable as root, so you will have to su to be able to use it.
su
enter password for root access
man fdisk
this will give you the full usage tools for fdisk, how to see what partitions exist etc.
if no swap partition exists then you will have to use fdisk to create it.

parted is another tool to create partitions, and may be the distro default tool.
but it is partitioning tools not volume management tools to use for this purpose.

tnx for your suggestion but the problem is that I already have 4 primary partitions and I cannot create one more. so I must create it in that logical volume group. any other suggestions would be helpful