This answer assumes that WebSphere and the JDE HTML WebServer are already installed and functioning...
On the AS/400, type the commands:
STRTCPSVR *HTTP *ADMIN (to start HTTP admin services)
then
STRTCPSVR *HTTP (jobname) to start each HTTP environment
-- jobname equals environment to be started. In our case, the commands we use are "STRTCPSVR *HTTP JDEOWPD",
then "JDEOWDV and JDEOWPY to start our 3 environments.
Should you require additional information, consult the "OneWorld JAVA Server Installation Guide (ISeries(AS/400)-Based Systems" documentation out on the Knowledge Garden.
Cheers.