Grammer mistake. Correct me

We would normally speak or write as follows:

I graduated in Computer Science in 2009.
I joined the company in 2014.

Not trying to be overly critical, but it is "grammar" not "grammer".

The two sentences should be written like this:

I graduated with a degree in Computer Science in 2009.
I joined the company in 2014.

Reasons:
1. Although you might come across a sentence like, "she joined in the game", that is an exception. You don't "join in" an established organization. You join an established organization. You join a company, you join a club, or a church.

2. In English, we do not capitalize nouns unless they are the title of something. So it's "graduation", and not "Graduation". While "I completed my graduation" is technically correct, it is much smoother if you simply make graduation a verb and write, "I graduated with a degree in Computer Science in 2009." Unless your education was interrupted for some reason and you want to emphasize that you came back and completed it, shorter is better.

3. Since we do capitalize titles, and we can presume the formal title of the course you graduated was Computer Science-it might even be the formal title of the department in the college you went to-it should be capitalized.

Having completed my Graduation in Computer Science in 2009, I Joined the company in 2014

Oops Ura, Blick is right about the "G" too