Tap the TikTok app icon, which resembles a music note. This will open your TikTok home page if you're logged into your account.  You will have to log into (or create) a TikTok account to create a video. If you haven't yet downloaded TikTok for your iPhone or Android, you can do so by using either the App Store (iPhone) or the Google Play Store (Android). Click here to be taken directly to TikTok's website, then choose "App Store" or "Google Play" depending on the device. It's at the bottom of the TikTok home page. Doing so brings up the filming interface. The Music menu will open. If it's the first time you're using TikTok, you may have to give the app permission to use your microphone and camera. You can choose music from TikTok's built-in library. Hit a song to preview it, and then hit Shoot with this sound to select it. By default, music from your library will start at the beginning. You can change the point at which your song starts by doing the following:  Tap the scissors-shaped "Cut" icon on the right side of the screen. Scroll right to the point at which you want your song to begin. The app will tell you "Beginning shooting from (time in seconds)." Tap the checkmark icon to save your changes.

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Write a summary of the previous text in Chinese:
打开抖音。 点击＋开始录制视频。 点击屏幕顶部的选择音乐。 选择音乐。 选择音乐的起始点。