are they correct?
When I went to school I found it difficult to keep my mind in my studies because I could spend hours messing around.

Sometimes I don't mind being alone so I mess about with my mobile phone and all its games

Question

are they correct?
When I went to school I found it difficult to keep my mind in my studies because I could spend hours messing around.

Sometimes I don't mind being alone so I mess about with my mobile phone and all its games

Answer

I believe so - messing around suggests just generally doing  anything that is not studying.
messing about  with the games on your phone suggests a concentration on a task but not with any real purpose.