Milan to Lake Como

I trained from Milan to Lake Como but it was years ago so this link is probably more helpful than my trying to remember my route
https://lakecomotravel.com/how-to-get-to-lake-como/#from-milan-train-stations

You should get Rick's Italy book as part of your tour package. He has lots of coverage of [edit] Varenna, our favorite place to stay there, including hotel and train details that you should read. From Malpensa, take one of the frequent Malpensa Express trains to Milano Centrale (FS) train station. Change there to a direct train to Varenna-Esino station (very small station, be alert to opening the door and jumping out). Direct, unreserved regional rains run almost hourly and most take one hour. Buy these tickets in the stations, about 13 euros for the first one and 10 or less for the second one.

"from Milan to lake como region for a fullday of sight seeing." - This is really not good to do as a day trip. And definately not onward to Padua on the same day.
Stay one or two nights.

Where on Lake Como? It is a big lake shaped like an upside-down Y

• Como town is at the bottom left, at the end of one of the arms. this is on the main rail route from Milan to Switzerland. It is a town, so not the most picturesque place on the lake.
• There is a different rail line from Milan going up the east (right) side of the lake with stops at all towns, including Varenna. This line continues to Tirano, and via the Bernina Line overthe Alps to Switzerland.
• There are no rail lines up the west side (left). You need to use buses from Como town, or ferries.
• Between the two arms is Bellagio.Again reachable from Como town by bus or ferry.

Whichever location you choose, from Milan airport you need to first take a train into Milan, then another train, and possibly a bus or ferry, to get to your destination.
To get to Padua, you return the same way to Milan, then a train to Padua.

You should get Rick's Italy book as part of your tour package. He has lots of coverage of Vernazza,

I suspect Laura meant Varenna

Yes, Joe, thanks.

Several years ago we stayed in the town of Varenna. There is an elegant old Italian villa with a wonderful ambiance and beautiful gardens that has been turned into a hotel named Villa Cipressi. Enjoyed our stay and would stay there again in a heart beat. The ferry to the other towns on the lake is just a short walk from the hotel.