3 sentences

1. 兄长过奖了，小弟实在不敢当。

   xiōng​zhǎng guò​jiǎng le, xiǎo​dì shí​zài bù​gǎn​dāng.

   You flatter me, brother; I really don't deserve such praise.

   Source: Dong Chinese Dictionary

2. 小弟初来乍到，还请各位多多指教。

   xiǎo​dì chū​lái​zhà​dào, hái qǐng gè​wèi duō​duō zhǐ​jiào.

   I am new here; please guide me.

   Source: Dong Chinese Dictionary

3. 他是我的小弟，比我小三岁。

   tā shì wǒ de xiǎo​dì, bǐ wǒ xiǎo sān suì.

   He is my younger brother, three years younger than me.

   Source: Dong Chinese Dictionary