i used color range to select the grays then entered quick mask and fine tuned the selection. exited quckmask, pressed ctrl/H to hide the selection and used color balance to change the color. then used hue and saturation for further adjustments and deselected next, using quickmask, i selected the background trees and changed the color to slightly green. i added images of park benches and with layer mask i dropped out the excess images and adjusted their positions and sizes. added some shadows under the park benches.. flattenned and saved.