Here is a tutorial on how to ice and smooth out your buttercream the easiest way possible.
Then you can get your cake ready to be covered with fondant or just leave it as is...
Remember, if you have never iced a cake before, don't get impatient...it comes with some practice...
I remember, first starting out it would take me a couple tries to get the cake perfectly leveled and straight...I got so frustrated at times...but don't get discourage and give up! It will come in time and you will be icing cakes in no time! ;)