A cut list is the bridge between a drawing and the lumber yard. It says what parts you need, what stock they come from, and how many boards to buy so everything fits with the least waste.
Start with the parts
List every part with its quantity, thickness, width and length, using the actual lumber sizes. Group parts by the stock they come from: everything cut from 1x10 together, everything from 1x4 together. A generated pattern already gives you this table.
Allow for the kerf
Every cut turns about 1/8 in of wood into sawdust. Two 36 in sides from an 8 ft (96 in) board use 72 in plus two kerfs, leaving about 23-3/4 in, not 24. Over five or six cuts on one board the kerfs add up to nearly an inch, which is the difference between a part fitting on the offcut and not. The cut list tool includes a kerf on every cut; change it if your blade is thicker or thinner.
Pack the boards
Put the longest parts on a board first, then fill the remaining length with shorter parts. This first-fit-decreasing rule is what the designer and the cut list packer use, and it is close to the best you can do by hand. The result tells you how many boards of each stock length to buy and what falls off each one.
Choosing stock lengths
Boards come in 6, 8, 10 and 12 ft. Sometimes two 8 ft boards waste less than one 12 ft; run the packer with each length and compare the offcuts. Longer boards are harder to carry and more often bowed.
At the yard
Buy one extra board for a first project. Sight down each board for bow and twist, and check the ends for splits, which can cost you a few inches of usable length. Let the boards sit in the room where the piece will live for a few days before cutting joinery so they settle to the same moisture.
Cutting order
Rough-cut every part an inch long first, then cut to final length in matched groups: all the shelves against the same stop so they are identical. Identical lengths matter more than exact lengths; a case with four shelves each 28-7/16 in goes together square, one with shelves varying by a sixteenth does not.