Ok, let's start from the begining...
1. Download SparkShare here: http://www.projectspark.ch/ss/releases/SparkShare-1.1.zip
2. Do extract the zip file you just downloaded
3. Right click on the extracted file, called SparkShare-1.1.exe
and choose "run as administrator". You can also simply click it normally, "run as admin" is to ensure enough rights are given to the installer to install the registry part
4. Once installed, you will find SparkShare installed in your start menu, under "SparkShare" folder, called "SparkShare"
I never heard about any of this, and if you don't use the installer to try to use SparkShare, SparkShare should start up and not the installer, it's simply not the same thing.