it looks like cron is already running, as long as the cron refers to the cron daemon. on slackware its crond. as long as its running, you dont run the scripts yourself, you wait for them to kick in at the hourly/daily/whatever intervals that are set by the folder you put your job in. crontab -e will let you change the times that the hourly/daily/weekly/monthly scripts are run. does your script that you want cron to run work? its independent of cron, your script should work just by typing ./scriptname or sh scriptname, then when you put it in the cron folder it will do the same thing as it did before, just at timed intervals.
at what times do you want it to run ? are you creating a file or producing some kind of output so you at least know if it has run even if your script doesnt do what its intended to ?