You can get to Marina Bay Sands SkyPark from either the Casino Taxi stand or from any point in The Shoppes.
From Casino Taxi Stand
Go through the MICE entrance and then walk to the MRT control station. Take the life/escalator towards Level 1, Hotel Towers. Proceed along the path outside Hotel Tower 1 and walk towards Hotel Tower 3. You will arrive at the SkyPark Observation Deck entrance.
From The Shoppes
Walk towards the MRT control station that is at Basement 2. Take the lift/escalator towards Level 1, Hotel Towers. Proceed along the path outside Hotel Tower 1 and walk towards Hotel Tower 3. You will arrive at the SkyPark Observation Deck entrance.
Walk towards the Mikimoto exit. Cross the street and walk towards the Hotel Towers. Proceed along the path outside Hotel Tower 1 and walk towards Hotel Tower 3. You will arrive at the SkyPark Observation Deck entrance.