running programs on REDHAT 5.2

[JOSE NG LEE]

I had installed before Linux Slackware 3.5 and run an executable file
without any problems typing the name of the file.  A few days ago,
I installed Redhat 5.2 Linux installation and try to run an executable
file but get an error.  

typed:   xfbb.sh
message: bash:xfbb.sh: command not found

typed:   exec xfbb.sh
message: exec:xfbb.sh: not found

Can someone give me some hints to run an executable file in
Linux Redhat 5.2.

JOSE NG / HP2CWB
e-mail:  [EMAIL PROTECTED]