It need to have spaces enter the following code and where it says filename substitute that for the name of your file that you want to install. That is if the file you have is in your Documents folder. This is the default folder that shows up when you click on N900 icon in file manager then the documents folder. If it is in just the main folder (MyDocs) ie the first one that shows up when you click on N900 in file manager then just use /MyDocs/filename.deb.