Each time you install or download anything, a notification icon will appear at the top of your screen. They are easy to remove in one of two ways.
1) Click the menu hard button, then "notifications" a window will appear, at the top of which will be a "clear all" button. Click it and they will disappear.
2) Click on the notification area and drag it down. If you have downloaded an app, clicking on the relevant notification will cause it to be installed. If you click and hold it you will be given the option to delete the notification.