In either the prayer input box or reply input box when you are ready to mention someone, type the "@" symbol where you would like their name to appear.
After typing the "@" symbol, a list of members will pop up. If you do not see the person you want to mention right away, continue typing their name until you do. Once you see the persons name select the desired user by tapping on their name. If you do not see them then they are not yet a member of your community in the app (invite them).
The user's name will appear in the text box in a blue color, which indicates that they have been properly mentioned and you can now continue typing.
When you are satisfied with your comment, click "Post".
Once posted, the tagged user will be notified that you have mentioned them.