Temat: szukam taniego przelotu we wrześniu na Majorke
Unfortunately, there doesn't seem to be a direct connection between the airport in Bergamo and Malpensa - and all train/bus connections go through the city centers in both Bergamo and Milan. So with only a few hours between your flights, you're going to be cutting it very, very close. If you can move your flight out of Malpensa by a bit, you'll probably be much happier...
To get from Orio al Serio to Malpensa, you'll do the following:
* Take the bus from the airport to Bergamo's train station (there's no train service to the airport).
* Take the train from Bergamo to Milano Centrale station.
* Either take a bus from Centrale to Malpensa, or get over to Cadorna Station in Milan (via the Milan Metro or taxi) and take the Malpensa Express train to Malpensa.
The bus from Orio al Serio to Bergamo is about 15 minutes, the train from Bergamo to Milano Centrale is about one hour, and the trip from Milan's city center to Malpensa is at best 45 minutes (that's how long the Malpensa Express takes to get from Cadorna to the airport, so it doesn't include your time getting from Centrale to Cadorna, & bus rides are likely to be upwards of an hour because of traffic). And assuming you need to be at Malpensa at least an hour before your outgoing flight there... Yeah, you're cutting it very, very close, indeed.
So, while the path I've outlined above would be your cheapest alternative (and really the only one via public transport), you might be better off looking into taxis that would get you directly from Orio al Serio to Malpensa, bypassing both city centers. It's not going to be cheap, but if you can't move your Malpensa departure then it might be your only option.
At the moment, the Orio al Serio website seems to be down, but the URL I've always used in the past is this one:
http://www.sacbo.it/