I don't know which guide you're using. However, if
-you have the last layer as the top layer
-and the top face is all one color
-and exactly two edges are unsolved
-and nothing else is unsolved,
here's what you need to do.
You need to take the edges out and switch them. If you don't know how to take out an edge piece, this video
will show you.
If that doesn't seem to be the problem, go through the same video
from the beginning. It probably has your answer.
If that still doesn't help, just ask again, and post a picture if possible.