Hi Barbie,
The X11 icon is normal; it's a program that opens at the same time as
Inkscape. You should be able to click the Inkscape icon in your dock to
get back to Inkscape. Inkscape *may* take additional time to open. In
particular, the first time that it opens, it may take several minutes to
open because it needs to scan all of your system fonts. (After that, it
will launch much more quickly.) So, be sure to give it a few minutes
the first time, and try clicking the Inkscape logo in your dock, to see
if that gets you to the program.
If Inkscape is really not opening at all, you may still need to install
XQuartz (a fancy new version of X11). Quit X11 (and Inkscape, if open),
and download and install this software, from the link that follows,
before opening up Inkscape again:
http://xquartz.macosforge.org/downloads/SL/XQuartz-2.7.1.dmg
Cheers,
-Windell