O.K. You got to blend the tune with the words. Some get the tune first others - other way round. Work out your phrasing and get a pattern going e.g. how many lines to your verse - what's the rhyming pattern in the song. A good way of starting to write a song is to look up some poetry and put some melody to those lines - then make up your own words.

Record yourself so that you don't forget any memorable chord sequences etc. Humm a melody line over your chords and build up a song in stages. Leave it , then go backto it a few hours or a day later. Listen to it again and you'd be surprised how you will get new ideas which will fill you with excitement. Remember we are not all like Dylan or James Taylor who can turn out classics in a few minutes. Song writing takes time and practice...just like learning to play an instrument. Good luck.