To install the two SSDs, you will need to remove two of the internal hard drive trays and screw the drives to the bottom mounting holes:

You will need M3x3MM size screws ( Make sure that the connectors are facing toward the handles.

Once both drives have been installed in the trays and the trays placed back in the drive cage, next thing you will need are two SATA data cables. You can purchase some here:

One end plugs to the drive, the other end will need to be plugged to an available SATA port on the motherboard.

Example motherboard

Next step is to grab a SATA power cable from the power supply bag that came with the computer. You will want to look for a cable such as this one:

The 6pin end of the cable will need to be plug to the power supply.

Remove the following screws for the PSU shroud to gain access to the power supply:

You will want to plug the cable to one of these ports on the power supply:

For reference as well: