How do I install the updated Hikashop to a Godaddy website.

First, I am not a programmer. Our website was half built over 3 years and abandoned by the company we contracted with to create it. I am a customer service person and they decided that uploading images was close enough and I am now the person looked at to untangle the web they left me.
I was told we needed to purchase the update for our Hikashop. We have 2.6.4 currently and did pay for the 3.0.1 version. Our company pays Godaddy to host the website and I was instructed to upload the Hikashop zip file to their site (done) but after that they told me I would need to find a developer to install it. Since they do not use Joomla, only Wordpress they cant help any further.

I have logged into our Joomla admin and hit the UPDATE/ABOUT button but it only redirects me to the sale site where it suggests I purchase and download it one more time. I have downloaded 4 copies now but the results are the same. It does not update the program on the Godaddy website. I am stuck in a circle here.

I would be very grateful if anyone can help, As the great George Jetson once said.. JANE GET ME OFF THIS CRAZY THING~~~~

Many thanks,
Pam

Error
There was an error uploading this file to the server.
Maximum PHP file upload size is too small: This is set in php.ini in both upload_max_filesize and post_max_size settings of your PHP settings (located in php.ini and/or .htaccess file).
Unable to find install package.



I went to extensions and tried to upload the zip file in both zipped and unzipped versions. It still will not upload. This is the error message it gave me.

Your version is 2.6.4, the latest stable version is 3.0.1

I now have uploaded it to Godaddy tmp file and gone back to my extensions on Joomla. Hit, UPLOAD and INSTALL. It says it was successful. But the page still says I have version 2.6.4.

Any thoughts on what Is happening?

Thank you,
Pam