You can simply delete the large files in your system but its a big trouble to find large ones easily. There is a program called 'TreeSize Free' that allows user to see where the disk space has gone to. You can start it from the context menu of particular drive or folder.
It will display the size of folders and its subfolders too. Along with size, TreeSize Free also shows you the other details related to folder or its files. It used simple Explorer-like style and all results drilled down to the file level.
You may apply filter to find a certain type of a file in your disk. With the use of column view, you can get the deep details of certain file or folder such as owner name and date of when file was last accessed. You can switch between your simple view and column view at any time and print your results. TreeSize Free also provides touch interface feature for Windows 8 and higher version users to get comfortable navigation.
Apart from this, you can scan your network shares and cloud drives such as DropBox , SkyDrive or GoogleDrive. It uses Master File Table in application that scan local NTFS drives in no time. Visit the official website of TreeSize to get more details and download link.