First you have to go to the window registry. Open the command prompt. Click on the start menu bar and pressing the window key +R. Typing “cmd.” Navigate to the location of the DLL files and hold the shift key “Open command window here. Type” regsvr32 dllname.dll” and press enter. regsvr32 adtschema.dll.
Press Ctrl + O and select your DLL File. Dll will be shown in left pane. Right click on Dll and select Export Source Code. Select the folder in which you want to export your files; Wait for a while it may take 2-3 minutes