Change path

I'm new to TextMate and Ruby so please bear with me.  I'm trying to run my
ruby code in 1.9.3.  When I run things now, it's running them in 1.8.7 for
some reason.  I don't know exactly what path should go in the Path but I
want it to run 1.9.3.  Please help.  I don't even know where 1.8.7 is coming
from