Installing Wuzly is extremely easy. Okay, so once you've downloaded index.php then you're ready to go. You'll need an FTP connection to your server, so start one up with your favourite FTP client. Then drag and drop! Boom! You now have a working blog (probably).
Okay, so there may be a couple of other tweaks you need to make. Firstly if you've got a big red bar at the top then you've got a permission problem. In order for Wuzly to save your blog posts, it needs write permissions. This is usually built into your FTP client, just right click the file and check the little checkbox next to write. Note that permissions can be dangerous so if you've don't know what you're doing then contact your hosting provider.
What about logging in? The default username is admin and you will be given a random default password when you download it. If you'd like to change the username or password, open the file in your text editor and you'll see things at the top called ADMIN_USERNAME & ADMIN_PASSWORD. I'll trust you can work out what those do. To login use the buttons in the bottom right of the screen. There are similar options for changing the title, the description, the colour and the amount of posts per page. So have a play around with those.