Spelling

I will talk about the problem is spelling. For the international students, the spelling is very difficult for us to remember. sometime when i was writing something, if i make some spelling mistakes. the sentences of meaning will be very different that what i want to write.
For example:

Their looking for a new sight where the gopher can build it's home.

it should be:
   They are looking for a new site where the gopher can  build its home.


The reason that i choose this problem is I always make the mistakes of spelling when i write the paper, then the reader always difficult to understand what i want to say. So for this problem, i think i should pay more attention for spelling when I want to write anything.