How Do I Partition Two Drives?

https://support.microsoft.com/en-us/help/17418/windows-7-create-format-hard-disk-partition

don't partition ssd, let it be, for hdd, I will do 3-4 partitions evenly.

Personally, I'm not a fan of partitioning physical drives at all. Doesn't serve a whole lot of purpose.

For the SSD, obviously leave it as one partition.
For the HDD, why partition it? Just have a few top level folders, for different things.

You can redirect your Doc/Music/Video/Downloads to save off to the HDD.
Win 7 & 8: http://www.tomshardware.com/faq/id-1834397/ssd-redirecting-static-files.html
Win 8.1 & 10: http://www.tomshardware.com/faq/id-2024314/windows-redirecting-folders-drives.html

Steam games can be installed and defaulted to the HDD as well:
Steam games location
In the steam client:
Steam
Settings
Downloads
Steam Library Folders
Add library folder

As above, don't partition your SSD. SSD's don't like that.

For the hard disk, if you want to do it the lazy way, you can just keep it as a single partition. Basically, when deciding on how much to partition/sizes, consider what sort of stuff you want to organize the drive around.

For instance, a very strong recommendation is to partition it appropriately if you make use of games, primarily through steam. In this way, if you have to reset your computer, you do not have to lose all your installed games to do it. You should additionally have a partition to keep your user files on, for largely the same reason.

As for size, that's something for you to judge. If your current or main PC is still in a working state, it might serve you well to check the size of:

C:\Users\<Userprofile>
C:\Program Files / (x86)

The first will inform you how much space you're generally using for your user files. The second will inform you of how much space you're using for your programs - this is largely moot as those will probably be on the SSD, but if you need additional space for them you can use a partition on your HDD. I tend to mount it into an NTFS folder (you'll see this option in the Create and Format... Partions tool I mention below) under "Program Files (HDD)" if needbe.

However, make sure if you have your games bundled in with that that you check C:\Program Files\Steam and do the math to get the separate figures for that.

Is this all the apps you'd otherwise install? If so, you can partition pretty tightly on that basis. If not, consider what you'd need for expansion. My experience has been, with just Windows and my non-games, 250GB is more than enough for the boot drive (aka: leave your SSD unpartitioned) and then... games and userprofile is something you'd have to determine.

Keep in mind you may lose data if you already have this drive in use when you repartition it. ALWAYS BACK UP.
In terms of doing the partitioning, when you're installing Windows you can use that, or later before you have all your stuff around, you can search for "Create and Format Hard Disk Partitions" in Start and it will bring up the tool to do this. Keep in mind the measurements are in MB, so make sure you're using the same units and be careful what you're formatting.

Getting data from a formatted drive is very awkward, so it's best you make a back up before you start if needbe, and look carefully at the sizes of the drives/labels to make sure they're the ones you want to wipe.

When you install the OS on the SSD, have ONLY the SSD connected.
Connect the HDD later.

Leave each drive as one single partition. It serves no real purpose to split them into parts.

You can delete the stuff on the HDD later, AFTER the OS is installed on the SSD.
What happens is...if you have both drives connected when you install the OS, the boot partition ends up on the second drive. You have little or no control over this, it just happens.
Later, when you try to wipe that drive, it will not let you.
Even later, when you wish to take that drive out and use it elsewhere, no boot for you.

Trust us on this...have only the SSD connected when you do the install.

For the partitioning? I don't know where you read that it works better, but no.