Please, read these articles:
SELECT[
^]
FROM[
^]
On the first look, your query should looks like:
"SELECT *
FROM itpJobs AS J LEFT JOIN itpJobCategory AS C ON J.jobCategory = C.jobCatId LEFT JOIN itpJobSubCategory AS S ON J.jobSubCategory = S.jobSubCatid
WHERE C.jobCatId=" + jc + " AND S.jobSubCatid=" + jsc + ""