How to infer formula from diagram
Each carbon atom (you seem to have identified them) needs four of those stick-like thingies (the lines, sometimes called "bonds"). These include the dashed lines and thick triangles as well as the "double bond" you see at the lower oxygen which looks like this ($=$). That one counts twice. Every time you only see 3 or even 2 for one carbon atom, that means 1 (or 2) hydrogen atoms are implied.