/.tuxpaint would be in your root directory... almost certainly wont exist.
from /home/user you may have more luck without the leading /
e.g. cd .tuxpaint
If it exists.

When you're in terminal you can use the 'ls' command to view what is there.
Note: files/directories with leading dots (.tuxpaint for example) won't show running ls with default options, so try ls -a (shows all files), ls -l (shows file properties etc) or ls -al (a combination of the two).