SMA LANDS ON WRONG RWY.

Narrative

I FLEW WITH MY FLT INSTRUCTOR TO GRANT COUNTY INTL ARPT FROM OUR HOME BASE OF ELLENSBURG; WA; BOWERS FIELD. THE PURPOSE OF THE FLT WAS TO SOLO AT AN ARPT WITH A CTL TWR IN ORDER TO MEET THE REQUIREMENTS FOR PRIVATE PLT. WE TAXIED UP TO THE CTL TWR; MY INSTRUCTOR EXITED THE PLANE. I TOLD THE TWR MY INTENTIONS AND THAT IT WAS MY FIRST TIME SOLOING WITH A TWR. HE INSTRUCTED ME TO DO MY STOP AND GOES ON RWY 36 WITH L HAND TFC AND TO WATCH OUT FOR A WDB DOING TOUCH AND GOES. I WAS CONCENTRATING HARD ON MY RADIO WORK; WHICH WENT VERY WELL. I TOOK OFF ON THE INDICATED RWY WATCHING MY LOCATION; CONCENTRATING ON MY ALT; AND BASICALLY TRYING SO HARD NOT TO SCREW UP THAT I ACCIDENTLY LINED UP ON RWY 3 WHICH BEGINS NEXT TO RWY 36; THE ONE I WAS SUPPOSED TO BE ON. I LANDED; THINKING I WAS ON RWY 36 THEN THE TWR CTLR INSTRUCTED ME TO BACK TAXI AND CONTINUE MY STOP AND GOES ON RWY 36. WHEN I RETURNED TO THE TWR SOMEONE HAD COMPLAINED OF MY MISTAKE WHICH WAS WORKING ON RWY 3 THAT WAS CLOSED FOR REPAIRS. CONCLUSION: I WAS CONFUSED AND CONCERNED WITH DOING EVERYTHING RIGHT THAT I MANAGED TO MESS UP.