To make balloons you need to put your looks over balloons image then it will be easy for you to make this . So we can start now with a curve to makes it as picture no 1.
Now make a draw of a curve in the left side as in the picture no 1 given like.
Make another same curve like its opposite as given in picture no 2
Make its face as like given in the picture no 3.
Then make string of balloons as shown in the picture no 4
Make a copy of balloon which of 1/3 should show out and rest of part should in back side which part will be never see for which we can see like the balloon is in the back of front balloon as like in the picture no 5.
Make like another copy which both side of left and right should be hide in the back of the front balloons as like picture no 6. Or you can make no 6 after the another copy of a balloon as it is shown in the picture no 7.
Make the balloon copies in the side as in the picture no 7
Then you can add the colors of your choice in each balloons.And the the balloons will show like awesome as the above picture.