大学生

Choose either おれor 私 or whatever and stick to it. 

私は大学生です。私の大学はフロリダにあります。You neither say: 'My university is Florida' ？

きれいです。Beautiful. Okay, but WHAT is beautiful? きれいな場所です？きれいな大学です？

People＝いる、Things,Buildingｓ＝ある。

大学には、先生達がいて、一本屋としょかてん(書家店？)？？？？があります。

あそこが二万人。That place is 20,000 people???? What is?

一人は私の友達です。彼女はきれいです。今日、私はバスで大学と書店／図書館に行きます。

Hey, there is also something called -online dictionaries- in case you didn't know.

Why are you writing stuff invented by yourself? 

Regardless of your level, unless very advanced, you better write your original version.

By doing so you are doing us two favors, helping people learn from your English and saving our time and energy breaking our heads to guess what you are trying to say.

That is the least respect you can show those who are doing you a favor.