Building a gate for a fence doesn't have to be a chore. A simple basic wood frame gate is a snap. A skill saw and variable speed drill are the only power tools you need, and the most important measurement is between the posts that the wood framed gate will fill. Be certain to subtract 1 inch from the measurement before cutting the material to size.
Place the 2-by-4 lumber on a worktable and space them out the distance needed to allow 6 inches above and below for the height of the gate. Be certain they are exactly the same distance apart from end to end.
Place a long 2-by-4 across the two boards from Step 1 to form a "Z". Mark this 2-by-4 so that when you cut it down it will fit between the other two to form a "Z". Once it is marked, cut it on the lines.
Stand the 2-by-4 from the previous step on its long edge. Drill two countersink holes on the ends.
Apply glue to the ends of the mitered piece, place it between the other two pieces and secure it to them with the 2 ½-inch deck screws. You should have three 2-by-4s in the shape of a "Z".
Place the pickets on top of the frame and space them out to suit your needs. If you need to cut any to make them fit, divide the necessary cut by two and cut the pickets on each end of the gate so that they are the same width.
Apply glue to the area of the frame where the pickets meet it and secure them with 1 ½-inch deck screws. Place the gate latch on the area it will be installed to see if you need to secure a 2-by-4 behind it for it to be sturdy enough to provide the security the gate needs.