How can the information be verified?

Click on an item in the Verification sources column to get the window shown below:

Additional information about the verification source

Here you can indicate how the data will be collected, and who will be responsible for the collection of this information.

To indicate who is responsible for the data collection, you can select any of your partners from the drop-down list.
Next, you can indicate the frequency at which the data collection should happen: weekly, monthly, every 3-4-6 months, yearly, at the start or at the end of the project, mid-term, before the project starts (ex ante) or after the project (ex post).
In the third text box, you can indicate what kind of information source you're using: a baseline study, registration forms, follow-up missions, meetings, etc.
If you've selected a website as your information source in the previous box, you can enter the site's URL in the Website box.
Finally, you can provide a bit more information about the collection method.