First off, practice makes perfect! Don't worry you will get better in no time!
Second, a great way to start out is using shimmery or matte shades that are similar to your skin tone. If you make a mistake, it isn't as noticable. I started off using a shimmery skin colored eyeshadow on the lid and a slightly darker brown in the crease. It is really fool proof!
Third, youtube is basically how I learned about basic makeup application. It is a really good source