Did your model come with one hard drive or 2? The JH comes with an SSD mSATA Raid card and an HDD. If yours only came with one drive, you should have a drive bay empty which you can fill. In that case:
Power down, turn it over, pull the rubber lip up, uncrew, put in new drive, put it back together and boot. Windows should see the new HDD, Format it, and you're good to go. Nothing else needed.
I dont know if the G750 with a single drive comes with both drive bay cages? I used a cut up nerf bullet to secure my second HDD in my G74. SSD's are very light and will not move around once connected. Just secure it in place with something pushing on it so it doesnt dislodge from the SATA connector and its fine. I ran like that for over 2 years without issue.
(ROG has simply become too expensive compared to the competition with same specs... 😞 )
MSI GE75 Raider 10SGS - i7 10750H - RTX 2080 Super - 32GB Ram - 1TB WD NVMe - 2TB 960 EVO - 300Hz 17inch Display
RETIRED: ALIENWARE R17 R5 - i7 8750H - GTX 1070 @ 1.9Ghz - 16GB DDR4 - NVMe 970 EVO 1TB - SSD 960 EVO 1TB
SOLD: ASUS G703VI-XH74K, RETIRED: ASUS G752VY-DH72, RETIRED: ASUS G750JH DB71 , RETIRED:ASUS G74Sx DH72