Top Cross
You are only focused on the four edge pieces one the top layer. when you are done it should look like:

DONT WORRY ABOUT THE CORNERS YET!!!
If it looks like:

Do FRUR'U'F' twice
If it looks like:
Do FRUR'U'F'
If it looks like:

Do FRUR'U'F' than U2 and FRUR'U'F' twice