Besides, you can tile tileset. Just Open Photoshop and do something like this.
<img src="http://i61.photobucket.com/albums/h53/Sodisna/example1.png">
Tile 'em in a square use a number that is power by ^2. (I.E. 32x32, 64x64, 128x128, etc)
Then when your down. Just select the background and make something other than the colors you're using in your tiles.
<img src="http://i61.photobucket.com/albums/h53/Sodisna/example2.png">
Boom. Import into Construct, set the tile to 64x64 (which what I used. You'd used whatever you set your tiles too.) and hit cut tiles. Select all the tiles, set a hotspot, select the mask color (which would be whatever you set your tile's BG color to.) and you're all set.