Cannot set permissions for .htaaccess file -please help

Hai I am new to ftp but I think I have learned enough to understand the basics. We can see that BizHat.com Free webhosting offers SSI, at the time of sign-up. But I am not able write on the .htaaccess file to enable SERVER SIDE INCLUDES on the server. My site does not take up a lot of web space, I am sure that will be not more than 5 to 10 mbs at the maximum, once I have completed my site creation. I dont think that's a matter of thought for the host. If anyone can help me enable SSI, I will be so thankful.
Since PHP is not allowed on our hosts, SSI is the only thing we can look forward to. Admin, please dont say no. Please reply.