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If you want to move something you've inserted in Grid, all you have to do is press and hold on something you aren't selecting and move it to a new location in the Grid.
Double tap on a tile that you have just created to get a larger view of it, images get bigger, people tiles give more information, text tiles can be edited in full screen and maps can be interacted with.
Tap on a tile you want to change such as a photo in this case to select it. Press and drag the green maestro circle up to bring up a menu of things that you can do with the tile, at this point a blue icon with a camera on it should show up, tap on this to enter the edit mode of photos where you can use your finger to pan around the photo or replace with another.
Tap on a tile you want to re-size to select the tile, the green circle should appear which you can press and drag up to bring up the maestro menu, look for the blue button with two arrows, you may have to swipe a few times to find it depending on the size of your selection, tap this re-size button to get some handles that you can drag to make the tile either larger or smaller.
Grids can be shared by tapping on the small person icon on the Grid menu at the bottom of the screen while being in a Grid. Type in the email or name of the contact from your contact list, and click submit in order to send the Grid to whoever you'd like to share it with. They will recieve a notification through email letting them know they can see and start interacting with your Grid.