Welcome to forums, hope you will enjoy learning/sharing knowledge/experiences here with us. Request you to please use code tags as per forum rules for codes/Inputs/commands which you are using into your posts. Following is the forum rules link (http://www.unix.com/misc.php?do=cfrules\) which you could through once and can see how important is code tags here to maintain the forums standards because it makes our life really easy to help/advice/solve/guide everyone. Coming to your question you could once use Search option present in the command bar too for checking these kind of solutions as this is one of the common asked question here, following may help you in same though.
awk 'FNR==NR{A[$1]=$0;next} ($1 in A){print A[$1] OFS $0}' Input_file1 Input_file2
Your welcome loktamann. Let me show you 2 ways to use code tags.
1st: While replying to any post or while opening a new THREAD etc, in TITLE bar you will see a button where it will be written co then down de.
2nd: Following URL on youtube will be very helpful for you to see how we use code tags