cursor focus

This is really a newbie question, but here goes..... I am running PHP4 with Apache on Redhat 6.2. I am sure I read this somewheres, but can't find it again. When I open a webpage in a small password application that I wrote, the cursor is not on the first text box I need to fill in, I need to click on the text box to begin typing. How do I get the cursor to "focus" on this text box? Many thanks in advance Ralph