1. The grid is your fabric, square for square
Every square on the chart is one cross stitch on your fabric. If a square is filled with a symbol, you stitch it; if it's blank, you leave that square empty. Count the squares — not the inches — to know where a stitch goes, because the printed size of the chart has nothing to do with the finished size of your work.
The heavier lines every ten squares split the chart into 10×10 blocks. They exist purely to help you count and keep your place.
2. Symbols stand for floss colors
Each symbol represents one thread color. A small key beside the chart pairs every symbol with a DMC floss number. Below is a worked example — an eight-square heart — shown the way a real chart presents it: a symbol grid on the left, the color key on the right.
To stitch it, you'd work every square in DMC 321 and leave the blanks empty. That's the whole idea — the chart never shows a picture, it shows which color goes in which square.
3. Start from the centre
Look for two small arrows on the edges of the chart — one on a side, one on the top or bottom. Where they line up is the centre of the design. Fold your fabric in half and half again to find its centre, then start stitching there so the finished piece sits centred on the fabric with even margins.
4. Solid lines are backstitch and outlines
Once the blocks of color are done, many patterns add straight lines drawn on top of the grid — usually a bolder color. That's backstitch: single straight stitches worked last to outline shapes and add fine detail like whiskers or lettering. A symbol filling only half a square is a fractional stitch, used to soften curves.