opening of downloaded files

Normally, to install applications in Ubuntu, you should use Ubuntu's built-in package management facilities, like the Software Center. To install RealPlayer on Ubuntu, see https://help.ubuntu.com/community/RealPlayerInstallationMethods. Please note that RealPlayer is no longer developed or supported for Linux-based operating systems (like Ubuntu), and furthermore, you should not need it--there are other, more current, typically free and open source ways to play realaudio and realvideo media. If you tell us what you want to do, we may be able to provide detailed information about your options.

I recommend against this unless you find that it is the only method that will fit your needs (and I don't know anybody who has actually found they need to do this), but you may be able to run the Windows version of RealPlayer in Ubuntu using Wine. First, install Wine in the Software Center. Then, download the Windows installer for RealPlayer. Then, right-click it and open it with Wine Windows Program Loader, and install it like you would install a Windows program. See http://appdb.winehq.org/objectManager.php?sClass=application&iId=180 for more information. Again, I only recommend you do this if you find that you cannot play your audio or video with programs available natively on Ubuntu (you should try https://help.ubuntu.com/community/RestrictedFormats and https://help.ubuntu.com/community/Medibuntu first).

How to open other files that you have downloaded depends on what kind of files they are and what you want to do with them, just like on any operating system. By default, your downloaded files will appear in the Downloads subfolder of your home folder. If you can provide more information about the files you have downloaded, then it may be possible to provide more detailed advice about how to open them. A detailed description of where you downloaded them (with URL's if possible) and their full names would be best, but if you can provide their extensions (the few letters just after the last . in the filename), that might by itself be sufficient for us to tell you how to open them.

adobe flash player is loaded but wont open you tube videos

@timothy burke
This is a separate problem from the one that P.ESAKKIMUTHU is experiencing, so please post a separate question about it (https://answers.launchpad.net/ubuntu/+source/flashplugin-nonfree/+addquestion). Please feel free to subscribe me to the new question.