I'm currently in windows 8, and I'm able to see my 3 main partitions.
But I don't understand why I can see the 1 TB partition in windows, but not in LMDE.
Also, the 50GB partition on my SSD appears to be empty, but I installed the "/" folder on that.
"/home" should be installed on the 1TB, but isn't visible.

/dev/sda6 is mounted as /, that is the linux root filesystem.
/dev/sda7 is mounted as /home, and is a 1TB filesystem. What do you mean by "isn't visible"?

Meaning I can't see it on my linux system.
As shown in the screenshot I posted on page 1.

sorry, that is not enough. For example what will say:
ls -la /home
df /home
(also try them as root)

Here's the output.

ignace@ivs-lmde:~$ sudo ls -la /home
[sudo] password for ignace:
total 12
drwxr-xr-x 3 root root 4096 Feb 26 12:29 .
drwxr-xr-x 23 root root 4096 Feb 26 12:31 ..
drwxr-xr-x 25 ignace ignace 4096 Feb 26 17:09 ignace
ignace@ivs-lmde:~$ sudo df /home
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/disk/by-uuid/80531cc2-093a-4820-8427-fb2ddd643b44 51474044 4239076 44597196 9% /

sorry, df -hT would give better result. Also please execute the command mount (just without any argument). I think /home is not mounted.
Than you can try sudo mount /home, but in that case your home dir /home/ignace will disappear. (I suggest you to use another mount point: modify /home, use for example /windows and also execute mkdir -p /windows before mount - as root). And probably the mount command will drop an error message too. (repeat the mount command)

Here's the output.

ignace@ivs-lmde:~$ df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/sda6 ext4 50G 4.1G 43G 9% /
udev devtmpfs 10M 0 10M 0% /dev
tmpfs tmpfs 790M 904K 789M 1% /run
tmpfs tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs tmpfs 1.6G 816K 1.6G 1% /run/shm
/dev/sda2 vfat 96M 26M 71M 27% /boot/efi
none tmpfs 4.0K 0 4.0K 0% /sys/fs/cgroup
ignace@ivs-lmde:~$ mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
udev on /dev type devtmpfs (rw,relatime,size=10240k,nr_inodes=1007540,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,noexec,relatime,size=808640k,mode=755)
/dev/disk/by-uuid/80531cc2-093a-4820-8427-fb2ddd643b44 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
tmpfs on /run/shm type tmpfs (rw,nosuid,nodev,noexec,relatime,size=1617260k)
fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime)
/dev/sda2 on /boot/efi type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=utf8,shortname=mixed,errors=remount-ro)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,nosuid,nodev,noexec,relatime)
none on /sys/fs/cgroup type tmpfs (rw,relatime,size=4k,mode=755)
systemd on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,name=systemd)
ignace@ivs-lmde:~$

So why is the /home mounted to the ssd and not the 1TB HDD, when I specificly asked for it to be mounted to the HDD

Screenshot of Gparted

Update:

Been searching around for the problem. Opened gparted and noticed that the 1TB HDD partition wasn't even mounted!
After some research I figured out that this was because of the partition still being used by win8.1.
I had to disable "fast boot" in windows, that way the partition was completely left alone.

So I reinstalled LMDE, but when I logged in, I got an eror saying that I don't have permissions on the /home/users/.dmrc file.
This is because the partition is ntfs ain't it ?
So what can I do to resolve this, I can't write permissions to a ntfs-partition.
So should I convert the partition to exfat ? If this is even possible ofcouse.

And thank for all the help, it helped me look in the right direction.

yes, I told you that was not mounted. Also I suggested a way to fix it...

Goodmorning everyone,

Sorry it took so long to answer, been kinda busy.

@pan64, I understood your solution and am very grateful you posted it, but since I clean installed LMDE, I no longer need to mount it no ?
The only thing that I cannot figure out is how to share files between windows & LMDE.

Windows is installed on 60GB SSD partition
LMDE installed on SSD (both root & home on seperate 25GB SSD partition)

Now, how can I move the user files from /home to the 1TB HDD ?
I know how to do this on windows, but I cannot figure it out on LMDE.
I was thinking about using links, but that would just make it copy the file from /home (on SSD) to another map on the 1TB, thus leaving the file on the SSD and still taking place on the SSD.

Again, sorry for my english, it can be confusing at times.
Anyway, thanks alot for all the help !