;( im a complete newbie
Ive downloaded the binary files from the site http://www.tcpdump.org
and untar the tar balls to a temp directory....from there i have run the ./configure, make and make install on both the libpcap file and the tcpdump file

Now how do i get it to sniff on my ethernet (eth0).....each time i use the command line it says that command not found? (tcpdump -i eth0) what am i doing wrong?

tcp dump is probably not in your path. You'll need to figure out where tcpdumps executables are located and run them from there. most programs get dropped in /usr/local/someplace. That or run a search for the executable. Most executables in user mode need to be run with either sh foo or ./foo I hope this helps!