My internship

It's been one month past (you could also say "A month has passed since...) since I came to the over here in US, so I decided to write down a diary entry.
I am working as a in guest relations.
Guests come to me with a whole bunch of questions every day. Answering them is really tough for me since English is not my first language. But I feel that I am improving my English skills day by day and am more confident than I was a month ago.
Today, I had a guest who had a disability person in the party (like the other guy said, party works, but most people say "group"). I took care of them for as long as I could. They looked very pleased and left a $20 gratuity ("tip" is a much more common word for gratuity) for me at the end.
When I got back home, I put it on the wall in my room. It will motivate me when I face to difficult situations at on my job.

Nice job :)

My Internship

It's been a month past since I came over here to the US, so I decided to write down the a diary entry.
I am working as a in guest relations.
Guests come to me with a whole bunch of questions every day. Answering them is really tough for me since English is not my first language. However, I feel that I am improving my English skills day by day and am now more confident than I was a month ago.
Today, I had a guest who has a disability person in the group. I took care of them for as long as I could. They looked very pleased and left $20 gratuetee for me at the end.
When I go back home, I will put it on the wall in my room. This will motivate me when I face to difficult situations at my job.

"party" is not wrong, but it is much more common to say "group".

Keep it up! Your English is very good.