sit down and study--first to learn to recognize the letters and associate them with the correct sounds and then to produce them yourself with pencil and paper.
stop for a moment and think about the differences between writing and talking, because those differences account for much that is difficult--or appears to be difficult--about writing.
first, writing is much slower than talking. it took me four times as long (44 seconds) to type the sentence that makes up the previous paragraph as it took me to read it in a normal speaking voice (11 seconds). and i do a lot of typing. try the experiment yourself. even with the wonderful tools available to 