To start, your user must be a Person as Copper only permits Opportunities to be connected to Persons.

When available, click Create Opportunity from the main screen:

On the following page, enter your opportunity details. In our example, we are opening an opportunity called Barcelona SaaS Deal with a value of 15,000USD at medium priority. The status is open, the source was advertising and we are placing it in the Qualified stage of the Sales pipeline.

When ready, click Create Opportunity and a success message will indicate creation:

The opportunity will now appear in the profile overview: