Joined: 01 Sep 2006 Posts: 2018 Location: Silicon Valley
DTL is a tag language. If you know HTML, DTL will look fairly familiar. Look at the DTL reference book. There are many short examples.
Also, all of the ISPF panels are delivered in DTL form... look at your SMP/E libraries for SISPGENU and SISPGMLI datasets. Use PANELID to find the name of a panel to use as a model and then find it in SISPGENU (it might embed files from SISPGMLI).
Put your DTL source into a member of a PDS. Compile using ISPDTLC command. The output will be a panel library member.