They are normally mounted on
For example, I have a windows drive which has the label "xtreme". This partition is mounted on
/media/cyrex/xtreme where cyrex is my username.
If you are in the Unity Desktop you should see something like in the Unity launcher:
It looks like a hard drive, if you click on it, it will automatically mount the partition on
/media/USERNAME. In my case, as I mentioned above, when I clicked on it, it mounted on the folder
/media/USERNAME/xtreme (As mentioned before).
Now, if you want to mount that sda2 somewhere else, for example in
/mnt, you can simply type in the terminal:
mount /dev/sda2 /mnt
Note that the 2 in sda2 means it is the second partition on that drive, which might mean it is the D: in your windows system (It depends on the other the hard drive was partitioned in the first place).
So if you have a C: and D: drives, assuming both are sda1 and sda2 and you want to mount them in
/media/rami/ then you would:
Create a folder for each (So you know which one is which)
Mount each one to the already created folders
mount /dev/sda1/ /media/rami/cdrive
mount /dev/sda2/ /media/rami/ddrive
note that there are many other ways of doing it, like setting the partitions to mount automatically via