Place your first stake into the ground in the place of your first pergola support.
Lay a carpenter's triangle on the ground so that the 90-degree angle corner touches the stake, and the arms of the triangle touch the imaginary walls of the pergola.
Tie a string to the stake and pull the string into line with one side of the triangle. Use the measuring tape and the string to locate the point at which the next pergola support will be. Mark this point with another stake.
Repeat this step for the remaining pergola supports.
At the location of each stake, dig a hole with post hole diggers that is 1/3 the length of your landscaping timber.
Fill the bottom of each hole with 2 inches of pea gravel.
Set each landscaping timber into the hole and brace with 2-by-4-inch boards so that each timber is at a 90-degree angle to the ground.
Mix the cement mix in a wheelbarrow with a garden hoe according to the directions on the package.
Pour cement mix into each hole by tipping the wheelbarrow forward to release the contents.
Reposition your timbers if they shift during step 9. Use your gardening hoe to tamp the cement and dislodge any air pockets. Then wait for the cement to cure before beginning the next step.
Lift two 4-by-6-inch boards to the top of the pergola supports on one side of your pergola. These two boards will form a single beam. Position them so that one is on each side of the support, and hold them in place at each end with your two woodworking vises.
Drill a hole through the beams and the supports.
Slide a bolt into each hole in your supports and beams. Secure the bolt with a washer and nut.
Repeat steps 12 through 14 for the two pergola supports on the other side of your pergola.
Position cap construction brackets along the top of your pergola beams so that half of them are on each beam. Space them exactly apart and across from one another on the beams.
Attach the cap construction brackets to the beams with wood screws.
Lift your 6 2-by-4-inch wooden boards to the top of the pergola and set them in the niche made by the construction brackets.
Secure the boards to the brackets with wood screws.