you probably already know this but my suggestions are

1) watch out, things are case sensetive so make sure you used cifsmount.sh and not Cifsmount.sh
2) to execute any script you must give the path of the script.

find the script first. do

ls

in the directory you're in to see the actual name of the script and to make sure it's there.

./cifsmount.sh

should work since the "." means current directory .

3) my final sugesstion is probably the more likely one since you seem to have found the script already but didn't have the privilages to run it. to me it sounds like you perhaps edited the script and added cifsmount.sh in it. did you?