Beginner's Solution
Step 3: Layer 2 Edges

After solving first layer, next we move on to solving the second layer. Since the 4 center pieces are already solved, what is left to solve on the second layer is only the four edges on the side.

Look at the U layer for these 4 pieces. Ignore the pieces with yellow stickers that belong to the last layer. The four edges that you are looking for is the blue-orange, blue-red, red-green, and green-orange piece.

First, locate the edge and align its side color with the center piece. Place the edge on your right. Then decide whether you are going to "shoot" the piece front or back:

Case 01: Shoot to front

R' U' R' U' R' U R U R

Case 02: Shoot to back

R U R U R U' R' U' R'

In the case of stucked piece, simply perform one of these two algorithms and shoot one random edge into the slot to bring the intended edge out into the top layer. Then repeat the process to insert it back correctly in its position: shoot a random piece from U layer to bring the stuck edge piece out into the U layer.