PHP Error, Notice: Undefined index: q

Am new to php and am using wamp as my server. I have the following code;

and html code as follows,
Home |

When i open the webpage for the first time, an error appears:
Notice: Undefined index: q in C:\wamp\www\prizeinfo\index.php on line 3

but if i click the link ‘home’ the error disappears. Please i need help on this.

Thanks