Instructions
Enter someone's place in "Roblox" if the place is shared and not copy-locked. Some people allow other players to go into the places they have built while that player is offline; this is indicated by a "Play Solo" option next to the "Play" button.
Click on the "Play Solo" button if it is an option for the person's building. You can access the construction tools to use in the other person's place.
Construct new rooms or add-ons to the person's build using the construction tools. Lay new blocks to create decorative items or new rooms for the building.