Total Neewbie needs help!!!

I just have little experience with Linux. I played around with another distributor.. The Ub..t..u...13.04.. But I changed to RHEL and I am afraid I might have to start learning curve all over again .

Here is my most immediate thing that troubles me... I can't get to install any application with a functional icon in the graphic GUI... For example, I downloaded Dropbox.. Although installation says that it proceeded ok, but I see no icon to start-up from the graphical desktop. Flash and Adobe Reader... I just don't know what I am doing wrong. Very confused figuring out the difference between RPM and YUM and BIN files and how they are properly placed , which folder and how to extract and install.

Please, your help will be greately appreciated.!!