Tiles are the door of your applications on Windows 8 new start screen. Tiles can easily interact with users via notifications even applications are not launched, notifications notify users regarding to latest updates/news. This is the good way to interact with user.


Let's have a look at how can we modify tiles and logos of our applications easily.

When we create a new Windows 8 Store App project, we'll have logos as default under Assets. In order to change these icons easily we can edit directly on these
files,

Or we can change logos via Application Manifest. 

 

 

We have different variety of logo sizes on our app. All of these files require certain sizes, we need to have exact resolutions for every single logo.

 
Here is the resolution list for logos: 

 

150x150px Logo - This is small tile on Start Screen  
310x150px Wide Logo - this is the wide tile on Start Screen
30 x 30px Small Logo - this is the logo when you list all apps on start screen or when you open search bar.
50x50px Store Logo - This is the logo when you submit your app on Store.
620x300px SplashScreen - This is the logo when you lanch an application
24x24px Badge - This is lock screen badge logo when you get a notification.

When you create a new logo, my suggestion would be use png files with transparent background, In order to change background color automatically through your application, this will be the easiest way to that.

You can get more information below

App tiles and secondary tiles: See Guidelines for tiles and badges
See Guidelines for secondary tiles.
Notifications: See Guidelines for toast notifications
See Guidelines for push notifications
See Guidelines for periodic notifications
See Guidelines for scheduled notifications