Hey Hazza Spazza, I got a question for you and other people. When you..

It should be in your pack

To find the weight go to the change tank screen and push circle.

You take the berry block you made, and feed it to your Pokemon, this will increase your Pokemon's perimeters. There are 5 stats categories your Pokemon has, depending upon how good they are in that area will determine how good they will do in the contest judging. Here are the 5 perimeters your Pokemon has when in contest Cool, Beauty, Cute, Smart, and Tough. There are types of contests that corresponds with the following stat categories, if you go into a Cool contest that�s for cool moves or and you don't have any and your Cool stat is low then you are most likely to lose use moves that go good with other contest types, and be sure to know what berries you are using if you use bad berries or not will blended ones then that will effect your stats badly, and a Pokemon can only use a certain amount of berry blocks until it's unable to anymore.

To answer both;

Go into Key Items,
Search for the Pok�block Case,
press A
select use
Choose block from list- press A
Choose give/use [can't remember]
Select the Pok�mon you want to give it to, then press A