Change Char in text box

[nuksies]

I want a character that has been enetered into a field to be changed into a '+' sign but not when viewed. What I want is for the user to type in a sentence and enter it and for it to open a different form and show a search engine with results of a search on the sentence, for example:

http://www.google.co.uk/search?hl=en&safe=off&client=firefox-a&rls=org.mozilla%3Aen-GB%3Aofficial&hs=5jT&q=this+is+an+example&btnG=Search&meta=

thanks for your help in advance
NUKSIES