help on below issues

[buygamingstuff]

guys i have sucessfully installed prestashop on my server after some long trouble

Now i have following issues

1. How can i make my theme to autosize ,I mean i want to cover complete screen not just in middle on your browser


2.How to change powered by prestashop to your own of some thing else


3.I had installed paypal module but in end i get below errors while doing checkout/purchase with paypal


Authorisation to PayPal failed

Please refer to logs:

1. PayPal response:
2. TIMESTAMP -> 2011-03-25T19:22:11Z
3. L_ERRORCODE0 -> 10002
4. L_SHORTMESSAGE0 -> Security error
5. L_LONGMESSAGE0 -> Security header is not valid
6. L_SEVERITYCODE0 -> Error
7. PayPal returned error


My shop :http://buygamingstuff.in/prestashop/

MY PRESTASHOP VERSION : 1.4V