go here http://www.csgnetwork.com/crongen.html and put in what you need click calculate copy it and in your terminal / putty window crontab -e at the bottom of the file paste in the info :wq and wait to see if its runs
crontab -e each task on its own line */2 * * * * /my/task1 */2 * * * * /take2/222 */2 * * * * /moot/11
Why do you want to have two crontabs for one user? You can put multiple cron jobs in one crontab, one per line.