XnViewMP could be fine but how can I instal it? I can't understand the forums sort of coding. I can't do it.
If you like XNView then download the deb package from here. If Ubuntu software center won't let you install it then do a
sudo apt-get install gdebi and open the
deb file with GDebi.
Another software for image editing is Pinta. You can install it with
sudo apt-get install pinta.
After all GIMP is the best solution, but if you do simple adjustments to images those two alternatives are good enough.
After that, just double click the deb file from nautilus, or if you prefer using terminal, just type
sudo dpkg -i XnViewMP-linux.deb
sudo dpkg -i XnViewMP-linux-x64.deb
from the download directory.
GIMP get your job done ?
It's also available at Ubuntu Software Center.