Hi nik0laus
15 GB are great (I thing about all SliTaz and a lot of personal doc's can be use easily there; it is enough for SliTaz, it would be enough for Kubuntu or Debian8)!
Steps:
- start as you did explain above
- at the commando line dialog step a few seconds later select F1 (to see the options) or directly "web"
- the web start can be a question of patience... don't renounce to early (I need sometime about 1/2 h to start a new web install ;-(( ... but as long you see points appear on the screen long minutes after long minutes, you can hope! from what it is depending? I don't know... If you have a dog, go with it for the daily walk and come after it is finish ;-) ...)
- if you have luck as you are again at home you see on the graphic screen an invite "Login" and proposed "tux" as user, he doesn't need some password, simply "enter"
- you are in a fresh SliTaz running in RAM, version according the selection you did made in the dialog following the commando line entry "web" immediately after start.
- if you see a text mode login, you also can continue but will probably encountre some supplementary problems, I am sorry ;-) ...
depending what happens (real graphic mode or commando line) the next steps can be different...
I hope real graphic mode for you ;-) ...
You can use gparted (applications > system tools >> gparted) to make you 15 GB usable by the new installation (format it as journalized partition: ext3 or ext4). I assume here as example it is partition 5 (the first partition in the extended partition, only an example, you can use what you want!)
If you did select the new slitaz-rolling-core.iso I did link in my precedent message, download it again directly into the partition 5 (I repeat: only example!!!):
mkdir /mnt/sda5
mount /dev/sda5 /mnt/sda5
cd /mnt/sda5
wget http://mirror.slitaz.org/iso/rolling/slitaz-rolling-core.iso
why (you are in slitaz-rolling-core!)? yes, you are in it but the kernel is already started and not accessible any more in the entirely in RAM running system :-) so you need to download a file containing the kernel :-) ...
and after that follow (but adapt them!) the steps describded in my second link out the version in you own language, it is more easy ;-) ...
1. extract and Install a copy of the kernel in the new /boot of the new partition
2. extract and Install all the rest in the root of the root of the new partition
3. adapt you boot loader (you did not indicate which one you are using but above page includes a good tutor for the installation so I suppose that that will end with success)
4. reboot as "tux" without password or as "root" with password "root"
alternatively
you can make all that steps in the comfortable environment of the graphical Slitaz Installer. "tux" loose here the ability don't to have to use some password and did require you enter some one. so, you, yourself, know the password you did give for both "root" and "tux" or possibly an other user (can be a cause of difficulties: I did create an other user, the same as in my other linux partitions... and it doesn't not word! for this reason I prefer to install manually!)
good luck!
and let us know if you have success...
kind regards