The basic format of the crontab entry is

minute hour day_of_month month day_of_week your_command_to_execute
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The '*' for the first five fields just means 'every'. So to run a command every day at 1:30 we use:

30 1 * * * some_command
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See man 5 crontab for a fuller description of the values you can use in those first five columns.

So now, the main part is what to put for "some_command".. i used this line, which is all part of a single find command:

find /home/march05/msc0516/public_html/Blast/updated/ -mtime 1 -exec /
+bin/rm '{}' \;
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This (man find) tells find to A) look in your Blast/updated/ directory, B) take files modified a day ago, and C) execute "/bin/rm FILENAME" for each one.

If you wanted to simply cron your perl script instead, it would be something like:

30 1 * * * /home/march05/msc0516/public_html/Blast/deleteFiles.pl
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Note also that the cron daemon will email you any output generated by the commands that are invoked by the crontab ... this is very handy for getting emails of errors.

note that google(cron tutorial) will yield a slew of results.