Ctrl+P
Open command palette ([Shift] + [cmmand] + [P]) and select "Extensions: Install Extension". Please type "VSlack" and click install button.
Open User Setting (File > Preferences > User Settings) and add
"vslack.selfToken": [ "your slack token 1", "your slack token 2", "your slack token 3" ],
Open command palette ([Shift] + [cmmand] + [P]) and select "VSlack". Select Slack team and channel or user. Send current file or selected text as snnipets or plain text.