How do you say

I bought a three months guaranteed red solid wood sofa online. It’s really well-made, and very comfortable to sit on.

..in Chinese?

我在网上买了一张三个月保价的红色实木沙发,质量很好,坐着很舒服。

wǒ zài wǎng shàng mǎi le yī zhāng sān gè yuè bǎo jià de hóng sè shí mù shā fā , zhì liàng hěn hǎo , zuò zhe hěn shū fú 。

How do you say "I plan to learn the guitar in the next three months." in Chinese?