Is this OK?

Dışarıdan görünse de sert birisi gibi, (why is the ´de´ here?)

İçinde çok neşeli ve mutlu birisi. 

Gülüşüyle motive eder bizi , 

Gülşen Hoca’mız sever hepimizi. 

On the outside she seems like a hard person,

Inside she´s very cheerful and happy.

Her smile motives us,

Teacher Gülşen loves us all.

De Here gives the meaning of "even though". Because it is a poem of some sorts, the word order is jumbled, normally it would be like this "Dışarıdan sert biri gibi görünse de". So it becomes, "Even though on the outside she seems like a hard person".

The rest is OK.