3 ways to share files

Drag and drop the file into the message box of a chat or channel post. Then, select Send  .

Select Attach   beneath the box where you type your message and then follow the cues to locate and attach your file. Then, select Send  .

Right-click the file in the chat thread and select Pin to make it easily accessible. 

After entering your message into the message box, right-click Send  . 

Choose a date and time from the dropdown menus.

Select Send at scheduled time.

Select Send  .