Concatenete text and payload

Hi i am a beginner in nodered, I would like to combine a text and a payload in a message to create an webos lgtv alert notification, i want to change "message":"Just Testing" with "message":"Just Testing & {{payload}}", node used is node-red-contrib-lgtv

msg.payload {"title":"Test Message","message":"Just Testing","isSysReq":true,"modal":true,"buttons":[{"label":"Dismiss"}]}
msg.topic ssap://system.notifications/createAlert

Thanks in advance and sorry if I wrote something wrong

You can apply the message items like payload and topic in a template node. This would entail putting these text values to the message parts into the same message then input to the template.

Thanks for the answer, I do not know if I understand well, I tried to create a template something is not right

[{"id":"df70b8da1fbe02c2","type":"lgtv-request","z":"2d0c3dfe7ecb14a9","tv":"d4a4b73e2368cd49","name":"LGTV","x":650,"y":200,"wires":[["ce46c453b99940a3"]]},{"id":"8f2a818f4e783ce0","type":"template","z":"2d0c3dfe7ecb14a9","name":"","field":"payload","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"\"topic\": \"ssap://system.notifications/createAlert\",\n\"payload\": { \"title\": \"Test Message\", \"message\": Test {{payload}} , \"isSysReq\": true, \"modal\": true, \"buttons\": [{ \"label\": \"Dismiss\" }] }","output":"str","x":420,"y":200,"wires":[["df70b8da1fbe02c2","ce46c453b99940a3"]]},{"id":"ce46c453b99940a3","type":"debug","z":"2d0c3dfe7ecb14a9","name":"debug 15","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":840,"y":140,"wires":[]},{"id":"746d6eba5c809a49","type":"inject","z":"2d0c3dfe7ecb14a9","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":240,"y":200,"wires":[["8f2a818f4e783ce0"]]},{"id":"d4a4b73e2368cd49","type":"lgtv-config","host":"192.168.1.100"}]

can you help me ?