Your SSD likely came with its own cloning utility, and you could clone your HDD over to it.
That being said, if you don't have tons of effort already put in to configuring the PC as it is I would suggest reconfiguring it with the SSD as the main drive, keeping the HDD unplugged for the moment, and:
a)
Completely Clean Win10 (Re)install Using MCT to Download Win10 ISO File
b)
Completely Clean Win10 (Re)install Using MCT to Create a Bootable USB Drive
Afterward you can plug in what had been your system drive and it will be recognized as a new secondary drive and assigned a letter.
You would have to reinstall your programs and re-create your account, but in my opinion, it's no more work at the early stages to do that and know that you have a completely clean Windows 10 baseline that was installed directly to that system SSD.
I will say, unequivocally, that the previous poster is incorrect. Whether one is using two SSDs, two HDDs, or those technologies in combination it is entirely possible to clone the existing system disc to what will be its replacement and have Windows 10 work perfectly well. I've done just that in the past. I still prefer to start fresh, though, if one isn't dealing with a system with years of user data and lots of installed programs already on it. The circumstance dictates which course I recommend and take based upon the total work likely to be involved.