how to 退税 as a student?

I am a student in the Netherlands. Last year, I worked as a student assistant for a professor from May to August. Back then, I don't know that as a student, I have the right to退税. So, Thank GGD. However, I don't how to do it. Should I go to the local government or somewhere else? Where can I get concerning info?

Thanks to anyone replying to me

你缴税了就可以退
找到你的工资单，
到税务局网站下载2007年退税的单子
到荷兰生活版，搜索作者是“死活水”的关于退税的帖子

Thank you for the tips. I will go and check it out.