Have a thumb drive, sd-card, a stack of dvds, or an external hard disk drive lying around? Great! Because if extracting files from your Lion download and installing the image onto external media sounds tricky to you, then we have a solution that better automates the process. Lion DiskMaker by Guillaume Gete proposes to take your Lion download and create a bootable installer on your media of choice.
There are few caveats, including that you'll need to have the Lion download handy in the /Applications folders (the Lion DiskMaker is best used right after the download finishes from the Mac App Store). Lion DiskMaker will also completely erase any media it makes bootable, so be careful not to overwrite any important information. The author recommends simply picking up a cheap 4 GB USB key from the store (your local Staples, Target, or Best Buy would do) since they're dirt cheap.
Lion DiskMaker has both French and English info pages on Serial Serveur if you want to get familiar with the software, or you can always use Google Chrome with its automatic Google Translate features built in if you want to read up. The software is simple to use: just run the app, select the media you want to make bootable, and let it do its thing.
And don't forget, we have a huge Q&A that answers your Lion installation questions.