Click on the link above, and when a box pops up choose "Save"

When the file has finished downloading, navigate to the download location of the file
(E.G. My Documents\Downloads for XP or YourName\Downloads for Vista/Win7).

Right click on the file "Laptimer3 64bit setup 121017.zip" (folder icon with a zipper on it) and select "Extract all...".

Click "Browse" when the box pops up, and select "Desktop" from the left hand list, and click "Extract".

This should make a folder on the desktop called "Laptimer3 64bit setup 121017"
Double click on the folder (plain folder icon) to open it.
Double click the install "Laptimer3_64bit_setup.exe"

Please note that 64 bit is only supported on Windows 7.