An informal letter

Dear Jane,

Sorry for not writing to you for a long time. How are you? What's new?
I want to write you about System of a Down's concert, which I attended a week ago. You know that I love rock, so you can imagine how was I feeling there. Actually, I went there thanks to Max. He had one extra ticket and gave it to me. The concert was a little far from me, in the center of the city, and I had to ride there for 3 hours (or it took 3 hours to get there).

Being there was awesome! I was dancing and shouting a lot. Before the concert, I had not seen the difference between attending live performances and watching them on TV. Now, I think when you see the live concert, you have unforgettable feelings (or Now, I think it is better to see the live concert).
Waiting for your answer,
Best regards, Kostya.

An Informal Letter

Dear Jane, Too formal!  Hey Janey dear!

Sorry for not writing earlier to you for a long time. How's life are you? What's new? Let me tellI want to write you about System of a down's [don't understand, so I'm guessing] a concert in downtown which I visited for went about a week ago. You know that I love rock and so you can imagine how was I feeling there felt! Actually, I went there Thanks to Max that I was there. He had one an extra ticket and gave it to me. The concert Though it was a little bit far from for me, in the center of the city, and it was worth it even I had to ride there for it was a 3 hours ride.

Being there was awesome! I was dancing and shouting a lot. Before the concert this I had not seen the difference between attending live perfomances and whatching them on TV no idea that it would be so different life than watching in the TV. Now I think when you After seeing a the live concert, you have there will be unforgettable feelings.

Waiting for your answer, [Again too formal] You can use some Russian here, equivalent to "ciao", "bye", "tata" etc.

Best regards, Kostya.