Yup, I indeed know jenkins.
You can use groups in testng.xml file to run your tests on the basis of groups as described
hereNow you can invoke testng.xml file from ant build. Refer this
example Notice
run target which specifies the testng.xml file. Now run target of ant build should be specified in build section of jenkins to run tests.
Does this answer your question?
~ seleniumtests.com