1 pick a color

2 search : (color name) tumblr

3 save pics you like

4 download the app pics art (the logo is a pink P)

5 once in the app press the + button

6 choose pic collage

7 choose grid 

8 scroll to find a six square grid

9 slide the border down to 0

10 click the center of the square to add pictures

11 make sure to use a least one word

12 press the top right arrow button ^^^

13 tap the gallery button to save

mood board examples: