Oolite Bulletins

I have just installed Realistic Shipyards and removed all the oxp's that would have been duplicated and installed the ones that are required but when it comes to Amen Bricks pirate clan one - the blitzspears, the file downloads as a .rar file? what do i do with it? should it be placed in the add-on folder with the oxp's or somewhere else? many thanks for any clarification (as you can probably tell - im no programmer lol)

please ignore this - just googled .rar and found out its another type of compressed file - downloaded a prog to unrar??? it and bobs your uncle