Letter: I started working here last weekend, I was lucky to get this job...

I need to hand this job tommorw so i decided to ask for your help.

24 October,2009
Dear Mark!

I’m sorry i haven’t written to you for a very long time. I have been very busy with my new job as a camp conselor.

I started working here last weekend, i was lucky to get this job because there were so many condidates applying for this position. My neighbour told me about his mom who is looking for a camp conselor at her job so i decided to try my luck. The payment isn’t so bad, i hope i will collect enough money to renovate my room.

During my time here it made me think how much my family is important to me. I’m very lonely here, unfortunately this place doesn’t allow you to maintain a wide circle of relationships as you used to have.

That’s all for now, i have to turn off the lights and prepare for tommorw.

Looking forward for your next letter

Best regards,

Peter!

This seems to be an informal (friendly) letter. If Mark is a family member then Best regards may not be appropriate, depending on the person. I know if I closed a letter to a family member with anything but ‘Love’ it would probably be taken the wrong way as my family members perceive ‘Best regards’ to be a more formal closing (used for a new friend, pen pal, etc).
Here is a link to help with formatting issues: englishplus.com/grammar/00000144.htm
Corrections: (I am not going to rewrite the letter for you, that IMO would defeat the purpose of “homework” which I assume this is)
Dear Mark, (should use a comma not an exclamation mark)
Make sure you capitalize all first person references-- I
Peter (doesn’t require any punctuation)
‘That’s all for know’ should read ‘That’s all for now’
Try not to change tense in the letter… Since the person in the letter has already gotten the job as a camp counselor, most of what is written should be in the past tense as the writer is reporting what has already taken place.
Re-read it and make sure that it ‘flows’ from idea to idea or sentence to sentence.

I am sure others on the forum will add more to what I have pointed out, but also make sure you follow your teacher’s instructions. Some teachers have a certain format that they like and you know your teacher better than anyone on this forum. Good Luck!

Mark is a friend in this case

Then Best regards would be appropriate.

You could also use:
Talk to you later,
Which may be more appropriate. I personally would not use ‘Best regards’ for a close friend, but would for like a letter to members of my building.