SHORT & SIMPLE
Forget "port multipliers"
Your ASRock H61M-HVS mainboard has ONE pci-Express socket of type "1x"; it is white plastic.
SEARCH ENGINE WORDS: pci Express SATA Controller card
A typical 1x slot can provide a pair of SATA drive interfaces.
Plug such a card in & secure its backplate with a bolt. Put new/next hard disk in a bay & secure. Connect data cable; card to drive. Connect power to drive. Turn on system. If that drive does not already contain your extensive hoards of animated GIFs, then just partition & format, and it soon will.
A modern motherboard should have at least one little PCI Express "x1" slot. POWER DOWN. PROTECT AGAINST STATIC. Open your system box, and see if your x1 slot is available (not already occupied).
The common, cheap PCI-E-to-SATA controller card is also known as "pci-E SATA HBA") and will be priced from $20 &up; e.g: StarTech has one around us$35; they tend to re-label common generic designs; maybe worth extra buck or two among low-end cards.
These cards likely do NOT come with SATA data cables. Get some.
Your box's power supply should provide SATA-power feeds. If you need to use a Y-adaptor cable to split-out power for these extra SATA drives, try to budget for splitting from SATA-power. Otherwise, a Y-cable splitting out from ancient 4-pin-Molex -to- SATA drive power is adequate and cheapest.
Some (other) mbrds offer an x4 slot; a tad longer than x1. An x4 slot can handle 8 additional drives, using a HBA-type pci-E card.
A hard drive's deepest power draw is at spin-up; modern drives hardly take much juice at all any more; don't worry about your power supply if adding only two or four more drives.
Performance: Good to very good (faster than Hashim's ASRock!)
Reliability: Good; don't touch tiny gold contact (slot) "fingers" with your fingers. Clean contact fingers only gently with solvent & lint-free cloth.
Win(ver.X): card package will supply media or a weblink for driver
Linux/BSD: Generally good support. Try to find out whose SATA controller ASIC ("chip") is being integrated in candidate card, and which model chip, then (example) search: Linux support LSI
Most of these chips bring their own silicon-level RAID options.
Under Linux/BSD, software RAID should work fine thru these.
HASHIM PLEASE NOTE: For win(ver.X) that ASRock mbrd's BIOS/SATA has a 3gig ceiling; see product website for "unlocker".
A modern pci-E x1 Sata Controller in your ASRock will suffer no such ceiling, and will not be limited like mbrd's integrated SATA.