Hello! I need a help!
I had
the task
to of write writing a
n application letter. My teacher marked
out my mistakes, but didn't correct them,
having told telling me "Go on a forum and ask native speakers."
I ask you
to help me to correct my mistakes.

1 - I considered
_________ and came to
a conclusion that I have
a good experience in work with children, so I
decide to apply for this job.

2 - As
I training in a gym, I could become
the sports leader.

3 - As to
the work beginning, you specified that work
begins since June 1. With the fact that I must study at college till 15 June, I could start
to work only
since 16 June.

4 - I really hope that you employ me
on this job.
That is The parts mark
ed out in red
color are my mistakes. Please, help me to correct them.