My friend, here’s how to get from LGA to 601 Madison Avenue, which is located between East 57th and 58th Streets.

Step 1: purchase a $4 MetroCard from any Hudson News stand at the airport and take the Q33 bus from the Main Terminal, or the Q47 bus from the Marine Air Terminal, to the 74th Street/Roosevelt Avenue subway station.

Step 2: at the 74th Street/Roosevelt Avenue subway station, transfer to the [subway line letter] (Color Line on the map). Take the Manhattan-bound (westbound) train from Roosevelt Avenue to Queens Plaza.

Step 3: at Queens Plaza, transfer across the platform to the "R" train (Yellow Line). Take the Manhattan-bound (eastbound) "R" train frfom Queens Plaza to 5th Avenue.

Step 4: at 5th Avenue, exit the subway and walk block east on 60th Street, from 5th Avenue to Madison Avenue. Turn right on Madison and walk two and a half blocks south on Madison Avenue from 60th Steet to 601 Madison Avenue. The building is on the eastside of the street.

I hope this information is very helpful.

Good luck
Native New Yorker