The first thing you need to do is create a template of how you want your grouping to look. You can do this by laying newspaper on the floor and arranging the pictures as you want them to hang. Your grouping may be of pictures that are all the same size, if you have different sizes you should balance larger pictures with several smaller ones.
Once you have them arranged, measure and record the size of each picture, the distance between each picture, and the distance between the picture hangers at the top, then mark the placement for each picture on the wall using a pencil. All that’s left to do is hammer in the hooks and hang your pictures. Use your level to ensure they are hanging straight. Enjoy!