Jimjam,
Reboot computer with Lion usb attached. When you hear the "chime" hold down the OPTION key. On the screen that displays, select "disc utility," which I think is the fourth option. In disc utility, select the SSD drive and format it. You want to use "Mac OS Extended Journaled" and under options select "GUID Partition" for Intel based processors. Once you format the drive, exit disc utility and you will be back to the screen you saw when you first booted. Now select the option that says to install Lion (takes about 10-15 minutes), reboot and you will be up and running after you enter all the set up info.
Good luck and enjoy the SSD.