Tie the string at this place, and it would be perpendicular to the house. Note the location of your first point, then measure out the line to mark the rest of the posts. Thee string should be on the outside of this post, so you must measure from the string in the middle of the posts. Mark this with a stake so you can see them. If the fence goes down the hill you have two choices, you can have the top of the fence to follow the slope of the hill, or you can keep the fence sections level and step the fence down at each post. If you like to scale down the fence, estimate the height different from the top and bottom of the hill, and divide this figure by the number of sections. And you get much going down the fence at each post.
Digging holes. You can use a clamshell digger to dig your post holes but this is a very difficult and fork if you have lots of holes, or you have hard ground it could rent a power auger, but you normally have to be two people to run it. In most areas you need to have post holes under the frost line to ensure that the position will be in place when the ground begins to heaven because of frost. As a guideline you should bury about half of the corner posts and about a third of the line post at the ground.
Setting posts. It is a good idea to put a 30-40cm layer of gravel in the bottom of each hole to prevent rot and decay. Gravel will allow water tat collects at the bottom of the hole to drain away. Set the end post first and set up position along the edge of the layout string. To prevent water from running down between the post and the concrete, you should fill the hole slightly higher than the ground and slope the top of the concrete from the rod a little. Brace the post in place while the concrete cures and how to build a fence. The line record does not need as much support. Normally the NOK to put them with dirt. Use a space to get a consistent distance between them and shovel dirt around them when you have posts in position. When you have 15 cm filled with dirt, packing dirt down and keep filling it up. When you have all posts set hard, trim the tops to get the right height.
Installing the panel. Stringers are the pieces you have horizontally between the posts and are to support your panel board how many you need and where to place them depends on the design of the panel. But you should have at least 5 cm below the bottom stringer to prevent rot and to make it easier to move. To attach the stringers, you should cut them to fit between the posts and nail them to posts. Remember to use galvanized nails. What the design of the panel you like to have is up to you, but it looks best if you keep the whole panel, consistent and symmetrical.