Adding basic UART Sample

Please don't collapse if statements
if (count == 26)
{
    count = 0;
}

also, I wouldn't use a count because it requires you to know how many items you'll end up with. Count is not the important thing, the character is.
How about
char output = 'a';
Serial1.write(output);
if (output == 'z')
{
    output = 'a';
}
else
{
    output++;
}