Blow up the balloon.

In the case there are leaves still on branches, use the scissors to cut the leaves off. 

For those that are using glue. In a separate bowl, mix equal parts water and glue.  For those using mod podge, you can simply pour it into a usable bowl.

Using the sponge paint brush, apply the glue solution to the balloon.

Then add each leave and liberally apply the glue on top of the leaf to hold it down.

Continue around the bottom of the balloon till you have the whole bottom covered.

Let it dry completely for 24-48 hours. Pop the balloon and carefully peel the balloon off the bowl.