How can I make route like this: take pax from port 1, unload in port 2, load new in port 2, fly to port 3 or port 1, it doenst matter.
The bolded one is what you can't do right now. There are bases instead.
When creating a route, you must always start and end in your base (the same where you depart). To do this, you simply open a new route, select the destination airport, and then choose the time and aircraft type and so on and click ok. The return leg (from destination to home) is created automatically in the process (you can see the return leg information when creating the route).
If you want to use a fuel stop, you must however choose the fuel stop-airport as your destination, and your final destination as the 2nd airport in the page it asks if you want to make a fuel stop.