ON IPHONE - 

1. in Slack App, click on you.

2. You will open the message to yourself, type in @Support ticket. 

3. Hit send.

4. click on the app pop up.  it will open and take you to the Support Ticket Home page. 
5. On the Home page of it, you can open a new ticket, Or you can follow up on your ticket, and you can ask the Knowledge Base. 

FYI: How to bring the App on the top of your Slack menu:
1. Right button click to open the pop up menu. 
2. Click on "Start conversation"

ADD THE SUPPORT TICKET APP TO SLACK IN PC -