CSD format is for the Poem, Huskygram, Singer EU, if you have a program like EMBroidery TrueSizer you can change it to your format. I don't remember where I downloaded it from but it was a free download. (one of the best things I ever downloaded)
RAR is a zipped file and if you click on it it should open up a file that you can use, like you use WinZip to open up ZIP files.
Hope this helps, good luck.

Have a look here.
First link is for unpacking, second for free conversion programms.

ttt

thanks everyone