How do I install Lion on a 2nd (SSD) hard drive?

I installed and formatted a 128 GB solid-state drive (SSD) on my Mac Pro. (My Mac Pro has four drives: a hard drive with Lion, a hard drive with Leopard for a legacy app, a hard drive for Time Machine, and the new SSD.) I went to the app store to download Lion to install on the SSD but I can't figure out how to download it. The download button says "Installed." Rebooting from the Leopard hard drive won't work because Lion can only be installed on a computer running Snow Leopard. (I tried to update the Leopard hard drive to Snow Leopard but for unknown reasons it won't let me.) I looked for the Lion Installer in my Downloads folder but I can't find it there. What should I do?

A good answer would be to return the SSD! I've spent hours trying to install this, to make my computer a couple seconds faster. The first 2.5" to 3.5" drive adapter didn't work because it was made for computers with cables, not for computers with sleds. Finding the right adapter was a challenge (and cost $40).