How to write in Tamil?

I am a Software Engineer working in an MNC in Bangalore, but my native is Tamil-Nadu. My team lead birthday was on last Wednesday. On his greeting card, everyone in our team was wishing him by writing some greeting words in their mother tongue in the card. Since, Tamil was my mother tongue, i started writing in Tamil. I forgot "How to start with ". I felt ashamed of myself. My head was completely blank that time.
I realized i am putting my signature in Tamil after 6 years.
When we were in school, we used to write some essays in tamil, that time only we used to sign in tamil. After that,we dont have chance to use it in the place of signature. Whatever form you fill up, it might be your college certificates or agreement or bank documents, you will be signing in English. We wont use our mother tongue language to sign.
Even this blog post, i m typing it in English. So kindly use few opportunities to write in your mother tongue, because you can also be unique from others by using your mother tongue and also you wont forget your mother tongue. I am not asking/advising  you to do this in all the places, but you can do this like wishing some person or giving greeting card...,

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