You should say:
When you received it
Who sent it
What it was about
Why it was important to you
1-4月雅思口语新题part2范文之：an important letter you received(紧张函件)
OK, well I suppose one of the most important letters I've received was an offer letter from a university I applied to—Leeds University, to be precise—so that's what I think I'll talk about.
And as for who the letter was from, well, I can't quite remember the name of the actual person who wrote it, I'm afraid, but if I'm not mistaken, it was sent by the university admissions office, who I guess are responsible for handling such matters.
Anyway, regarding what the letter was about, well basically, it was just informing me that I had been accepted onto their Master's program in Finance, so it was really great news for me, because this was the course that I most wanted to study, and out of all the various universities that I applied to, Leeds was definitely top of my list, as it was the one that most appealed to me, in terms of both the course content and social life.
So, as you can imagine, I was over the moon after receiving the offer. I mean, it felt like all the years of hard work I've put into my studies seemed to have finally paid off, so it was like a dream come true for me, it really was.
And finally then, with regard to why this letter was important, well, I think it goes without saying that it was extremely important, because essentially, it means that I'm gonna be able to study abroad, which I'm sure will have a huge impact on my future career, as it will hopefully enable me to apply for jobs which I wouldn't have otherwise been considered for.
And as well as this, I reckon that studying abroad will help me become more mature and independent, which I've noticed has happened with a few of my friends who have spent some time abroad, and I'm sure this'll have a positive effect on my life in general.
So it's a big opportunity for me, and I'm really looking forward to it!