Hi, I need to show who is online at the avatar in post.

Like this (only a green dot):  

 

Here: 

 

 

Which code include?

Maybe this:  {{if $loadedMember->isOnline()}}<i class="fa fa-circle ipsOnlineStatus_online" data-ipsTooltip title='{lang="online_now" sprintf="$member->name"}'></i>{{endif}}?

I installed this plug-in. It seems to work flawlessly and not only does it tell you the online status, it also indicates what kind of device somebody is using. It's brilliant and I recommend it very highly unless you think that reporting what kind of device people are using is too intrusive

https://invisioncommunity.com/clients/purchases/70253-mix-advanced-online-indicator/