First step to build your electronic project is getting some reference and start draw your project schematic. You can use Eagle software (Free Version) to draw schematic and create PCB. But Eagle Light edition limited to 100 x 80 mm (4 x 3.2 inches) area and only Top and Bottom wire (2 sides PCB) and the schematic editor can only create one sheet if you are looking more features PCB and Schematic Editor with GPL license you can try Kicad.
Kicad is an open source (GPL) software for the creation of electronic schematic diagrams and printed circuit board artwork. The software designed and written by Jean-Pierre Charras. Kicad is a set of four softwares and a project manager: Eeschema (Schematic editor), Pcbnew (Board editor), Gerbview (GERBER viewer), Cvpcb (footprint selector for components used in the circuit design), and Kicad project manager. This software able to handle schematic diagrams and Printed Board up to 16 layers. You can also simulate your project in 3D viewer using PCBnew (just like Eagle 3D)
This free electronics design software is very useful for everybody who working in electronic design and student whot start to draw their first schematic. Kicad runs under LINUX and Windows (XP or 2000).