How to "align" a Linux file system with a SSD?

yes you need to align - ssds [more to 32kB or 64KB than 4kB alignment - depending on underlying flash] and big hard-disks [usually 1.5TB or larger, to 4KB boundaries] and disks in stripping raids [RAID1, RAID5, to strip-length probably 32-128kB] should be aligned too.

why to align? read here.

how to align? check this.

They probably mean set the block size to 4k. http://en.wikipedia.org/wiki/XFS#Variable_block_sizes

I think the default used to be 512Bytes for a lot of file systems but people moved to using 4k. There should be a way of setting it when you create the filesystem.