To install Magento ECommerce you need to login to your hosting control panel first.
Once logged in look for the Softaculous App installer Icon:

Click this to install Magento ECommerce

Next, click on the blue icon next to the domain on which you would like to install Magento ECommerce.

Click on the Arrow next to E-Commerce.

On the screen that opens you will find a list of categories on the left side. Click on the E-Commerce Category to open it.

Next, click on the Magento link.

Click on Magento

Now click on the small Install link as shown here:

Click the Install link

On the page that appears, IGNORE the fields called “Database Name” and “Table Prefix“.

A very important field is “In Directory”.
Here you enter the name of the folder in which you want to install Magento ECommerce.
In the example below it would end up in:

http://helpinghost.com/magento/

IMPORTANT!:

If you leave the field “In Directory” EMPTY and it will be installed into the root of the website and become the new homepage. So in our example it would be:

http://helpinghost.com/

Last, click the Install Button on the bottom of the page and wait a moment.

Fill in the some of the fields like Usernam/passowrd, admin Email, Last Name and so on and click install when done.