Yes you can, there are few plugins that let you add HTML codes to block on website such as Widget Anywhere,.. Now, you can add Ads block, Traffic counter or anything. Also, there are a option let you add HTML codes in header, footer and few position, could be found at Admin -> Layout (yousite.com/admin/layout).
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.