Sending the message to other user in the community is pretty much straightforward task. There is however, several ways you can send message to the user.
Sending From User Profile
The most common way to send the message to a user is to visit their respective profile page and locate the Send message button
Once clicked, the button will call the popup for creating the private message
In the popup displayed above, you must write the message Title and the actual Message and just click on the Send button
Sending From User Lists
In various JomSocial user list, such are, but not limited to, friend lists, group member list, event attendee's lists etc... you can also find the Send Message button. It looks like this
Sending From Inbox
You can also send private messages directly from inbox
When youre in your inbox, navigate to the Write link
In the following window, the similar for as in popup will appear only this time, with one additional button to allow you adding recipients.
You can send the same message to multiple recipients too