Every country in the world has its own culture and traditions. So, birthday celebration of people from each country is different. Thai People also has our own way to celebrate our birthdays.
The birthday celebration in thailand some Thai people celebrate birthdays by going to a nice restaurant and having a great meal with friends and families. Some Thai people have birthday parties. They prepare cake with candles and gifts. Besides, as majority of Thai people is Buddhist, on our birthdays, we usually go to temple to make merit such as offer food to monks.
For me, birthday parties at night I usually celebrate with cake, and presents and gift like most. But at the morning (or at noon) if have times I usually go to the temple to offer food to a monk or make merit.
If you come to Thailand during your birthday, you can try celebrating your birthday as a Thai by offering food to monk in the morning. It is one of the ways to learn our culture and it is not difficult to do. Just follow other Thai people. We usually take off our shoes while offering food to monk. Do not forget to do so!