You can sell tickets directly from your own website with a simple iframe.
Here is the code you need (you can also find it when you're logged in to Freshtix under the 'Marketing' tab - see below)
<iframe src="https://www.freshtix.com/events/MY-EVENT-URL?iframe=true" height="400" width="100%"></iframe>
Click the 'Promote' tab under 'My Events'
Once you update it on your website, it will look like this when an event is live!