Click on contacts at bottom right corner of page. Your friend list will pop up. The names in color at top are the ones online at the present time.( You need to refresh often. Refresh buttom right top corner of chat list.) Pick person you wish to chat with, double click. Chat box will appear on left of screen. Also, orange flashing at bottom of left screen, click, someone is wanting to chat.You can double click on people not on line and chat box will appear, you can type and next time they get online it will pop up for them to see. I hope this helps in some way. I also had no way of knowing what to do until a fellow italki person taught me. Thanks Dennis where ever you are.
If no toolbar at bottom, go to top right of screen, between coins ITC and INBOX is an italki bubble. That is chat on(outlined in pink) and chat off(outlined in blue). Click to pink and toolbar should pop up.