Step 1: Select "Chat" on the Side Menu
Step 2: Choose an existing chat, or start a new one by clicking the blue Compose icon
Step 3: Click the Location icon to the left of the text field
Step 4: Choose either "Request User's Location", "Attach a Pin", or "Attach my Location". If you select "Attach a Pin", you can choose an existing pin. "Attach my Location" will add the location automatically
Step 5: If you wish to include a message, type your message in the text field and you can send the text and pin attachment in one go
Step 6: Hit "Send"