Sql Server 2005 Developer Edition

I have installed and re-installed this SERVER four times now and I am unable to even use it. On the second install I had a "SQL Server Management Studio" on my START menu that I could click on and start the server but I had no connection to the server so I was unable to use it. Now on the forth re-install even that is gone and I am unable to find the .exe file on my hard drive in the "programs" section. During installation it called for SP 3 which was successfully installed but I also downloaded and installed SP4 but it did not help. My OS is Windows 7 Home Premium. I know that I am using 2005 edition but that is all I can afford. I'm out $172.00 for it. Can anyone help me on this? Have a good day.

PS. I just purchased SQL SERVER 2012 Developer Edition from Amazon and a book on how to use it. What I need now is instructions for installing SQL Server 2012. Do I install it on top of the current version or do I go into Control Panel and delete anything that looks like SQL Server 2005 and then install the 2012 version, or do I need to reformat the hard drive and reinstall my OS as well as all of my apps? If I have to do the latter then this takes the better part of a weekend but I have done it at least 10 times since 1992 when I got my first PC. Best to all of you.