Я бы перевела так (кое-где немного поменяла смысл, так что лучше перечитай):
"Dear Mary!
I want to
invite you to visit me in Ekaterinburg . Besides you want to
go to
Russia, aren’t you ? I have holidays in the summer, could you come in June?
Here is
very good in the summer! I have already made a plan! I 'll show you
Yekaterinburg,
which is the capital of the Urals . We will visit the Museum of Stone Carving
Art and the
major temples and monasteries. You will see
natural
park " Deer Streams " .
Another my friend invited us to his dacha , which is
located on the shore of
picturesque
lake "Baltic" . We will cook shashliks, swim and
sunbath . Also
I’ll introduce you to my friends. We will have fun !
If you
agree , then write more . I'll tell you how all things should be done. We will
take all
your
expenses in Russia . Besides you will live with my sister , we have
have
prepared for you a separate room.
You friend,
Lena."