2 sentences

1. 请在对话框输入验证码。

   qǐng zài duì​huà​kuàng shū​rù yàn​zhèng mǎ.

   Please enter the verification code in the dialog box.

   Source: Dong Chinese Dictionary

2. 请在对话框中输入你的用户名。

   qǐng zài duì​huà​kuàng zhōng shū​rù nǐ de yòng​hù​míng.

   Please enter your username in the dialog box.

   Source: Dong Chinese Dictionary