Level 1266 is the first level in Diamond District and the 601st jelly level. To pass this level, you must clear 17 double jelly squares in 24 moves or fewer.
When you complete the level, Sugar Crush is activated and will score you additional points.
Use the first few moves, preferably five, to clear as much marmalade, and unlock and reveal as many mystery candies as possible. These will already help you take out the blockers. If a special candy comes out of the mystery candies, use it to remove a layer or popcorn, or create a special candy combination to clear layers off multiple popcorns.
After the first popcorn is unlocked, a colour bomb will take its place. Use the colour bomb wisely, detonating a colour that will yield many cascades, or combining it with a striped candy.
At around five moves remaining, there should be many cascades due to the number of colour bombs on the board. This will help you clear the rest the jellies.