Download Legacy Floating Sandbox Ships, Vol. I Ship Pack

Download the ship pack by clicking on the link above
Locate the download in your browser's Downloads folder
Unzip the ship pack to a folder of your choice (if you don't have a zip utility, you may download WinZip for free)
Start Floating Sandbox
Open the Ship Load Window (go to the File menu and choose Load Ship)
In the Ship Load Window, locate the folder where you have unzipped the pack at step 3 above, and load the ship you want!