EasyEDA Std has no awareness of PCB stackup structure, dimensions or materials. You start by deciding how many layers you think you will need (2, 4 or 6 layers are the standard stackups offered by JL:CPCB but they can do more layers on request): Set up the required number of copper layers in the Layers tool in the PCB Editor; Do your layout. If you need controlled impedance then refer to: [https://cart.jlcpcb.com/impedance?_ga=2.2870328.984181257.1655828094-1235809702.1641493522](https://cart.jlcpcb.com/impedance?_ga=2.2870328.984181257.1655828094-1235809702.1641493522) and: [https://cart.jlcpcb.com/impedanceCalculation?_ga=2.263579524.984181257.1655828094-1235809702.1641493522](https://cart.jlcpcb.com/impedanceCalculation?_ga=2.263579524.984181257.1655828094-1235809702.1641493522); You will have to manually calculate the widths of - and route - any controlled impedance tracks. My preferred tool for controlled impedance design is MDTLC: [https://sourceforge.net/projects/mdtlc/](https://sourceforge.net/projects/mdtlc/)<br> <br> * If you are on a budget then do not use the autorouter as this will probably use more layers than you can get down to with a careful manual routing job. * It is also strongly recommended that unless you have considerable experience in PCB layout for controlled impedances or Signal Integrity, you do not use the autorouter and instead do your routing manually.

hi if you mean the board outline width, you can use board outline tool at tool menu, or use the track to draw the board outline at board outline layer