If it's normal sata ports underneath the adapter, you can connect it inside as a secondary drive if you like.
In the end it should look like this.
The smaller cable is your Sata data cable, this connects the hard drive to the motherboard providing you got a space and also providing you motherboard supports Sata connections.
Looks like this.
The larger cable is the power cable, this you may need an adapter to convert the normal power cable to sata like below.
Also if you think you might have the need to do something similar in the future or use any hard drives you find, you can invest in a multiport adapter which has connections for normal IDE, laptop IDE and sata drives.
Multiport adapter looks like this.