setting point 3.3

Please help me, I still confuse for setting this point 3.3

3.3. You can define _SENDTELEGRAM with value 1 to you host/services template OR create telegram-service and telegram-host templates which can be joined to your host/service. Variable _SENDTELEGRAM will be used as mark = 1 (see point 2.3). So only particular hosts/services will participate in telegram notifying.

Thank’s