要使用BWWalkthrough库创建引导页，可以按照以下步骤进行操作：

1. 首先，确保已经将BWWalkthrough库添加到项目中。可以通过Cocoapods进行安装，或者手动将库文件添加到项目中。

2. 创建一个新的UIViewController来显示引导页。可以按照以下代码示例创建一个名为WalkthroughViewController的类：

import UIKit
import BWWalkthrough

class WalkthroughViewController: UIViewController, BWWalkthroughViewControllerDelegate {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建引导页视图
        let walkthrough = BWWalkthroughViewController()
        self.view.addSubview(walkthrough.view)
        self.addChild(walkthrough)
        
        // 设置引导页内容
        let page1 = BWWalkthroughPageViewController()
        page1.title = "Page 1"
        page1.content = "This is the content of page 1"
        page1.image = UIImage(named: "page1")
        
        let page2 = BWWalkthroughPageViewController()
        page2.title = "Page 2"
        page2.content = "This is the content of page 2"
        page2.image = UIImage(named: "page2")
        
        let page3 = BWWalkthroughPageViewController()
        page3.title = "Page 3"
        page3.content = "This is the content of page 3"
        page3.image = UIImage(named: "page3")
        
        // 添加引导页到引导页视图
        walkthrough.add(viewController: page1)
        walkthrough.add(viewController: page2)
        walkthrough.add(viewController: page3)
        
        // 设置代理
        walkthrough.delegate = self
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        // 显示引导页
        let walkthrough = BWWalkthroughViewController()
        self.present(walkthrough, animated: true, completion: nil)
    }
    
    // 实现BWWalkthroughViewControllerDelegate的方法
    func walkthroughCloseButtonPressed() {
        // 引导页关闭按钮点击事件
        self.dismiss(animated: true, completion: nil)
    }
}

3. 在需要显示引导页的地方调用viewDidAppear方法。例如，在AppDelegate的didFinishLaunchingWithOptions方法中调用：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // 创建引导页视图控制器
    let walkthroughViewController = WalkthroughViewController()
    
    // 创建窗口并设置根视图控制器
    window = UIWindow(frame: UIScreen.main.bounds)
    window?.rootViewController = walkthroughViewController
    window?.makeKeyAndVisible()
    
    return true
}

这样，当应用启动时，将会显示引导页视图控制器，并在视图出现时调用viewDidAppear方法。用户可以通过关闭按钮关闭引导页。