I decorated my first cake for my first Wilton Course I. However, when I went to put a base layer of bc on my cake, the icing would not stick. I used the big tip and then tried to smooth it out with a spatula and it just kept pulling off the cake making me have crumbs in the cake. Any suggestions???? 
Was your cake just baked? Was your icing too heavy? Was your cake frozen? These could be some of your problems.When you use the larger icer tip I have found that it helps to get as close as you can to the cake without actually touching it.If you are putting on a crumb coat, the icing needs to be fairly thin, once that coat crusts, you put on a heavier coat to cover any crumbs. If you are using the spatula, you need to stay behind the icing, if the spatula touches the cake it will pull off crumbs. I hope this helps some, check with your teacher also, she should have shown you how to ice a cake. Also there are good tips in the Wilton yearbook.
I would recommend that you add some light corn syrup to your icing. Beat it in well. The amount is going to depend on what you're starting with and what consistency you want to end up with. The corn syrup will help to loosen up the icing without making it "grainy", which can be a real problem when you are using food coloring in your icing.
I would also suggest you take a small amount and thin it down considerably with the corn syrup, then use a spatula to spread a VERY thin layer on the cake. This, as you probably know, is called a "crumb coat". Make the icing thin, but NOT runny or you'll have a real problem. Once you've got a decent crumb coat on, chill the cake for about 20 minutes to set. Now use the cake icer tube to put your now-thinner icing on the sides. That should help you out.
Last suggestion, you might want to try a different icing recipe. I went through a TON of different recipes before I finally settled on one that I liked the taste and consistency was what I wanted. If you want, PM me and I will be happy to get you the icing recipe I use now. It's great for everything from icing to writing to roses, and everyone who likes the typical sweeter icing (shortening/powdered sugar-type) tells me it's their favorite.
Good Luck and Keep Baking!
Odessa
Thanks for all the help. I will try these suggestions this week! Thanks again.
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