Well, what are you upgrading from? If it's Windows Home Server, are you using its client backup feature? And if so, is this something you want to continue?
What do you use your server for, and are there any new capabilities you want to take advantage of?
OK here is my problems
I have an old dell 1430 server with a 256mb ssd drive and 2 3MB hdds.
the ssd drive is where I would install win 10 . what do I have to do to make this (upgrade) to win 10 go as smoothly as "possible"?
I can put the OS on a hdd also this is a store bought version of win 10 home.
I wouldn't go for Storage Spaces - there have been reports of issues when a disk goes bad (and I too have had that sort of problem). You can go down the RAID route if you have the hardware controller to support it - don't go for software RAID. Alternatively, have a look at Stablebit Drivepool which give you the flexibility of duplication at the folder level or across all storage. If you have data that doesn't need to be protected, you don't have to sacrifice the space for duplication of that folder.