Need to show other columns for SUM

Postgresql 8.4.

Thank you for the help. This did what I wanted:

SELECT j.armasterid, substring(j.ccdescription from 1 for 15) as desc, j.ccpromisedate as promdate, j.ccmasterid as jobid, sum(jc.jcactcost) as sumactcost 

FROM job j

JOIN jobcost jc ON (j.ccmasterid = jc.ccmasterid)

WHERE (j.ccpromisedate BETWEEN '2014-07-01' AND '2014-07-05') AND (jc.jcactcost > 0)

GROUP BY  j.ccmasterid, j.armasterid, j.ccdescription, j.ccpromisedate

ORDER BY j.ccmasterid ;

I just have to add the other columns I want to show in the GROUP BY clause.

Everyone has different ways of learning, and I didn't find what I needed via Google. In case you were wondering, I learn better by example, and this example will help me a lot in other things I have to do. Thanks!