I'm so clueless. I'm trying to make a cake for my dad for fathers day and all the fondant attachments keep cracking or breaking. How do I solve this problem??? And also..what's the best way to adhere the fondant pieces to one another?

the fondant is probably too dry. You can knead in a small amount of shortening into a ball of fondant to add moisture.

sticking pieces together just takes a tiny bit of water. You can also use a bit of royal, if you have it already.

Adding a little bit of glucose to the fondant would help too, if you have any.

You can stick fondant together with a little bit of meringue powder dissolved in water, or some egg white if the piece isn't going to be eaten.

but the cake calls for dried fondant pieces. Will the glucose/ shortening help to prevent the cracking when it dries as well?

yes, Don't add a lot of either shortening or glucose. just put some on your fingers and knead the fondant. you will feel it become a bit softer and more pliable. The pieces will still dry.