How to Make Your First Selection and Replace Blocks in WorldEdit

Selecting a region

WorldEdit edits happen inside a selection, so you always start by defining one. Stand at one corner of the area you want to change and use the wand (or the position commands) to set the first point, then walk to the opposite corner and set the second point. The two points define a rectangular box. If you want a flat wall or floor instead of a full box, you can expand the selection in a single direction afterward.

Replacing the blocks

Once the selection is set, run a replace command. The basic form takes the block you want to remove and the block you want in its place. For example, replacing one common block with another will swap every matching block inside the selection. You can also replace only blocks that match a pattern, or replace everything in the region with a single block type.

Checking before you commit

Large replacements can be hard to undo mentally, so preview the region first. Use the selection outline or a count command to see how many blocks will change. If the number looks wrong, your corners are probably off. When it looks right, run the replace. If you make a mistake, undo immediately rather than trying to fix it by hand.