I relly want to be good at songwriting but i cant get my foot in the door i have troble mixing music and words i relly want to write a good rock song but i cant think of any words wich dont suck can someone help me?
just write what ever comes in your head, and I mean the first things. If your righting about a topic, your first thought is usually your biggest opinion. Kurt Cobain is a great example.

He wanted to write how his musical success was the result of his teen years. How did he say this?

"Teenage angst has paid off well"

This song was Serve The Servants, so if you want to look it up go ahead. Some songs really didn't make any sense. So you could put the most random crap on the lyric sheet and there you go. Another Nirvana song, "Beeswax"

"Gluing my manhood to ze manhood. And pepe le pu said hey! hey! hey! then we clash! I got my diddly spayed!"

Did itt makes sense? No, unless it was some spaceshot metaphor. But it was a killer punk song, with a distinct riff.
It doesn't matter if the words suck - Write them anyway.

You can't just one day decide to start writing songs and then churn out brilliant lyrics, just like you can't pick up an instrument and play great music. It takes practice.
Bob Dylan would fill note book after note book of ideas songs themes stories some pictures, draw from personal experience use your vocabulary.

Generally I find when matching words with music get the music and hum along for a while or put some oohs aahs whatever try to find a good sounding melody then spend some working on some ideas and themes for the song. Sometimes a few words will jump out in the melody while your trying to work it out and boom you got a hook.

If you have say an idea for a line of words sometimes the words wont go right and you'll have to find other words to fit in with the phrasing.

There's all different ways to write the best way is to write write write play play play and keep refining your skills everytime you write a song next time try and write one a little better keep going like that and soon you'll have some brilliant songs.
It sucks hearing this but unfortunatly it's something you have to practice too. I don't know anyone that is instantly "good" at it you need time to find what works for you and your own personal thing. Write a little something everyday, always keep a piece of paper on you and every little musical idea that appears jot down and work on writing your lyrics a bit more every day. But really people just want to hear something being said its not always about whats being said so dont get to stressed out over it, just let it flow. Much luck to you.
"Those people who tell you not to take chances
They are all missing on what life is about
You only live once so take hold of the chance
Don't end up like others the same song and dance"
Just write it down, you can always edit later, but for now just write down every line that occurs to you. I just started writing a few months ago after playing music for ten years. I had always wanted to write but felt I couldn't, then I had to write a few songs for a charity thing, so I just started. Already the difference between those first songs and my more recent ones is amazing. Just write it down, edit, and practice.